PR #164: Move readme contents to documentation project (resolves #138)

* Copy readme contents to Dev Resources
* Move under User Guide->Package Reference
* Point to new package reference docs

---------

Co-authored-by: Stephen Metcalfe <raithlin@outlook.com>
Co-authored-by: Hazel Koehler <acomputerdog@gmail.com>

Documentation/Dev Resources/index.md

@@ -1,3 +1,3 @@
 # Dev Resources
 
-This section contains tables, FAQs, and useful information for developers.
+This section contains tables, FAQs, and useful information for developers.

Documentation/User Guide/Package Reference/ActivityPub.Client/index.md

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+# ActivityPub.Client
+
+This package implements logic and services necessary to implement an ActivityPub client.
+[Everything is available through DI](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Client/ClientModule.cs) for simple, abstract usage.
+
+## Available Services
+
+| Service                                       | Implementation                                 | Description                                                                                   |
+|-----------------------------------------------|------------------------------------------------|-----------------------------------------------------------------------------------------------|
+| [`IActivityPubClient`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Client/IActivityPubClient.cs) | [`ActivityPubClient.cs`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Client/ActivityPubClient.cs) | Implements an HTTP client that automatically parses JSON-LD and constructs ActivityPub models |

Documentation/User Guide/Package Reference/ActivityPub.Client/toc.yml

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+items:
+- name: Overview
+  href: index.md

Documentation/User Guide/Package Reference/ActivityPub.Common/index.md

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+# ActivityPub.Common
+
+Contains types and logic needed by multiple ActivityPubSharp packages.
+Unlike [the internal utilities](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/InternalUtils), this module is available to user code.
+It is loaded implicitly by most other packages, but you can initialize it manually through [CommonModule](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Common/CommonModule.cs).
+All important services and configuration classes are bound through DI.
+
+This module does *not* publish a package.
+Instead, its included as a dependency by other packages that need it.
+
+## Available Options
+
+| Options Class                                    | Configuration Path    | Description                                       |
+|--------------------------------------------------|-----------------------|---------------------------------------------------|
+| [ActivityPubOptions](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Common/Util/ActivityPubOptions.cs) | TBD - not implemented | Common, general-purpose ActivityPub configuration |

Documentation/User Guide/Package Reference/ActivityPub.Common/toc.yml

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+items:
+- name: Overview
+  href: index.md

Documentation/User Guide/Package Reference/ActivityPub.Extension.Mastodon/index.md

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+# ActivityPub.Extension.Mastodon
+
+Implements type models and logic of Mastodon's ActivityStreams extensions.
+This package is required for functional communication with ActivityPub servers.
+
+This package is not yet implemented.

Documentation/User Guide/Package Reference/ActivityPub.Extension.Mastodon/toc.yml

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+items:
+- name: Overview
+  href: index.md

Documentation/User Guide/Package Reference/ActivityPub.Server.AspNetCore/index.md

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+# ActivityPub.Server.AspNetCore
+
+Implements middleware to integrate with ActivityPub through ASP.NET Core.
+
+This package is not yet implemented.

Documentation/User Guide/Package Reference/ActivityPub.Server.AspNetCore/toc.yml

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+items:
+- name: Overview
+  href: index.md

Documentation/User Guide/Package Reference/ActivityPub.Server/index.md

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+# ActivityPub.Server
+
+Provides services to implement an ActivityPub server.
+
+This package is not yet implemented.

Documentation/User Guide/Package Reference/ActivityPub.Server/toc.yml

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+items:
+- name: Overview
+  href: index.md

Documentation/User Guide/Package Reference/ActivityPub.Types/index.md

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+# ActivityPub.Types
+
+Models and serialization logic for ActivityPub types.
+Out-of-the-box, supports the base and extended ActivityStreams types including collections.
+Supports simple JSON-LD in the compacted form.
+Provides a [pre-configured serializer](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/JsonLdSerializer.cs) to convert between models and JSON.
+
+## Usage
+
+This package is loaded automatically by higher-level packages.
+For standalone usage, call [`TryAddTypesModule`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/TypesModule.cs) to register all services for DI.
+
+## Built-in Types
+
+Standard ActivityStreams and ActivityPub types are modeled under the `ActivityPub.Types.AS` namespace.
+Types are implemented as classes and grouped as follows:
+
+* [`ActivityPub.Types.AS`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS) - base types.
+* [`ActivityPub.Types.AS.Collection`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/Collection) - Collection / page types.
+* [`ActivityPub.Types.AS.Extended.Object`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/Extended/Object) - Extended Object types. These all derive from [`ASObject`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/ASObject.cs).
+* [`ActivityPub.Types.AS.Extended.Link`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/Extended/Link) - Extended Link types. These all derive from [`ASLink`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/ASLink.cs).
+* [`ActivityPub.Types.AS.Extended.Actor`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/Extended/Actor) - Extended Actor types. These all derive from [`APActor`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/APActor.cs).
+* [`ActivityPub.Types.AS.Extended.Activity`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/Extended/Activity) - Extended Activity types. These all derive from [`ASActivity`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/ASActivity.cs) or one of the synthetic types described below.
+
+## Synthetic Types
+
+To improve developer experience, a few synthetic intermediate types have been introduced to the hierarchy.
+These are as follows:
+
+* [`ASType`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/ASType.cs) - a common type between [`Link`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/ASLink.cs) and [`Object`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/ASObject.cs). This enables support for the `Range: Link | Object` construction that is common within the ActivityStreams specification.
+* [`APActor`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/APActor.cs) - base type for Actor objects. Defined object types may extend this directly, and any other compatible object (includes Inbox and Outbox) will be "promoted" to include this as a standalone.
+
+## Entities
+
+### Overview
+
+In addition to the "model" types described above, ActivityPubSharp includes a second, lower-level type model referred to as the "entity system".
+This feature can be ignored in most cases, but it is absolutely critical to use or implement an ActivityStream extension.
+
+### Usage
+
+The most common usage of the entity system can utilize a mid-level "easy path" - three special functions that are defined on all types.
+
+* `Is<TModel>()` - returns true if the object includes a provided model, either as a base / super type or as an entirely separate type defined in the `type` property.
+* `Is<TModel>(out TModel? instance)` - same as before, but also constructs and returns an instance of the target model. Follows the `TryGet` pattern.
+* `As<TModel>()` - same as before, but returns the constructed model instead of a boolean. Throws an exception if the object doesn't contain the provided type.
+
+These functions should be sufficient to comfortably work with most valid ActivityPub objects, even polymorphic ones.
+All related instances are automatically linked - that is, changes to one instance will be reflected in all others associated with the same object.
+This is true even for base types and instances that are constructed later.
+
+
+### Implementation
+
+Entities are implemented as an extra **sealed** and **non-inheriting** class associated with each type.
+By convention, they are named the same as the type class with an `Entity` suffix.
+For example, `ASObject` has an associated entity called `ASObjectEntity`.
+Entities are typically placed in the same file as their associated type because the two are tightly coupled.
+Typically, application code will not need to work with entity types directly.
+However, it will be necessary if implementing a new extension or handling some rare edge cases.
+
+### Models vs Entities
+
+* Models utilize **inheritance**, while entities use **composition**.
+* Entities are automatically constructed during JSON conversion, while models are lazy-constructed on-use.
+* Within a single type graph, entities are singletons while models may be duplicated.
+* Models represent the "expected" shape of an AS object. Entities model the "actual" runtime shape.
+
+### Entity Mapping
+
+APSharp includes a 4-step process to determine which entities should be constructed from an incoming JSON message.
+All entities detected by at least one test will be converted and parsed.
+1. Map values of the `type` property to registered AS type names.
+2. Try all entities that implement [`INamelessEntity`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/Overrides/INamelessEntity.cs).
+3. Try all entities that implement [`IAnonymousEntity`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/Overrides/IAnonymousEntity.cs).
+4. Try all configured [`IAnonymousEntitySelector`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/Overrides/IAnonymousEntitySelector.cs) instances.
+
+## Utility Types
+
+These types are implemented to support certain special-case properties.
+Most exist for DX only, although a few are needed for type-model accuracy or serialization purposes.
+
+* [`ASUri`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Util/ASUri.cs) - (will) implement the namespaced IRI concept used in JSON-LD. For now, just a wrapper around `Uri`.
+* [`JsonLDContext`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Util/JsonLDContext.cs) - provides a consolidated view of the JSON-LD context associated with an object.
+* [`JsonLDContextObject`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Util/JsonLDContextObject.cs) - encapsulates the `object | IRI` typing used in the JSON-LD context. Does not parse or enforce IRI correctness - its just a `string`.
+* [`JsonLDTerm`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Util/JsonLDTerm.cs) - encapsulates the `object | IRI` typing used in JSON-LD term definitions. Does not parse or enforce IRI correctness - its just a `string`.
+* [`Linkable<T>`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Util/Linkable.cs) - encapsulates the `Range: Link | T` construction used in ActivityStreams.
+* [`LinkableList<T>`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Util/LinkableList.cs) - encapsulates the `Range: (Link | T)[]` construction used in ActivityStreams, as well as the extra cursed `Link | T | (Link | T)[]` variant.
+* [`NaturalLanguageString`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Util/NaturalLanguageString.cs) - models BCP47 language-tag mapped strings.
+
+## Collections
+
+ActivityStreams Collection types are implemented in the [`ActivityPub.Types.AS.Collection` namespace](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/Collection).
+All four basic types are modeled, and the implementations support extensions like any other type.
+
+Collections are, currently, a weak point in the library.
+They are fully implemented and functional, but the API is not particularly ergonomic.
+One notable limitation is that ordered and unordered collections do not have a common base type, which makes it difficult to implement code that handles either form.
+Another limitation is `TotalItems` - if unset, it returns the size of `Items`.
+But once set to any value, it cannot be reset to null and therefore the original logic is unavailable.
+These limitations will be resolved at a later date.
+
+## Extensibility
+
+### Overview
+
+ActivityPubSharp includes support for most valid ActivityStreams extensions.
+Custom types are supported, and extensions of built-in types can be emulated by inheriting from the original type.
+JSON-LD contexts are followed while constructing extension types, although property names are not currently remapped.
+
+### Usage
+
+At startup, the module scans all loaded assemblies and registers any type deriving from [ASType](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/AS/ASType.cs) and implementing [IASModel](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/IASModel.cs).
+Registered extension classes will be automatically constructed by the [polymorphic converter](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/Converters/TypeMapConverter.cs).
+Polymorphic extension types will be handled by the Entities system described above.
+
+Extensions types should include a link to the context that defines them.
+If the extension in question is not properly defined (has no context), then it can be excluded.
+However, extension classes without a defined context will instead be placed into the ActivityStreams context, which will apply them to
+**all** objects.
+
+See the [ActivityStreams documentation](https://www.w3.org/TR/activitystreams-core/#extensibility) for more information on extensibility.
+
+## Limitations
+
+* Several properties and edge cases are not correctly handled. See the [issue tracker](https://github.com/warriordog/ActivityPubSharp/issues) for details.
+* Only a minimal subset of JSON-LD is supported. For full compatibility, it is necessary to override the default [JsonLdSerializer](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/JsonLdSerializer.cs) and pre-process the incoming JSON.
+
+## Available Options
+
+| Options Class                                                    | Configuration Path          | Description                                                                |
+|------------------------------------------------------------------|-----------------------------|----------------------------------------------------------------------------|
+| [JsonLdSerializerOptions](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/JsonLdSerializerOptions.cs) | N/A - not mapped by default | Options for the default [JsonLdSerializer](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/JsonLdSerializer.cs) |
+| [ConversionOptions](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/Overrides/ConversionOptions.cs)   | N/A - not mapped by default | General JSON / JSON-LD conversion options                                  |
+
+## Available Services
+
+| Service                                               | Implementation                                          | Description                                                           |
+|-------------------------------------------------------|---------------------------------------------------------|-----------------------------------------------------------------------|
+| [`IJsonLdSerializer`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/JsonLdSerializer.cs) | [`JsonLdSerializer.cs`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/JsonLdSerializer.cs) | Parses and serializes ActivityStreams messages from JSON or JSON-LD.  |
+| [`IASTypeInfoCache`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/ASTypeInfoCache.cs)   | [`ASTypeInfoCache`](https://github.com/warriordog/ActivityPubSharp/blob/main/Source/ActivityPub.Types/Conversion/ASTypeInfoCache.cs)      | Indexes metadata related to AS / AP types defined in the application. |

Documentation/User Guide/Package Reference/ActivityPub.Types/toc.yml

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+items:
+- name: Overview
+  href: index.md