Fix link issues and update README after moving to GH pages

On hard reload the URL ending with `xyz/` sometimes becomes `xyz`, which
then breaks all relative internal  links. With this change, we are
adding `gatsby-plugin-catch-links` to ensure internal links work either
way. Also we update the readme to reflect where the website is now
hosted.

README.md

@@ -27,11 +27,9 @@ npm run serve
 
 ## CI
 
-The website is automatically built at and deployed to Netlify.
-A preview of each PR is deployed to Netlify.
+The website is automatically built with [Github workflows](.github/workflows/) and deployed on Github pages, which are reachable via [theia-ide.org](https://theia-ide.org/).
 
-In addition, every commit on `master` is built and published to branch `gh-pages`, which will soon replace the deployment of Netlify.
-A preview of every pull request is published at [eclipse-theia/theia-website-previews](https://github.com/eclipse-theia/theia-website-previews).
+A preview of every pull request is published at [eclipse-theia/theia-website-previews](https://github.com/eclipse-theia/theia-website-previews). You'll see a comment with the link to the preview once the build is finished.
 For more information, see [`publish.yml`](.github/workflows/publish.yml) and [`preview.yml`](.github/workflows/preview.yml).
 
 ## License

gatsby-config.js

@@ -20,7 +20,8 @@ module.exports = {
                 plugins: [
                     'gatsby-remark-autolink-headers',
                     "gatsby-remark-external-links",
-                    "gatsby-remark-prismjs"
+                    "gatsby-remark-prismjs",
+                    "gatsby-plugin-catch-links"
                 ]
             }
         }

package.json

@@ -25,6 +25,7 @@
     "gatsby-remark-prismjs": "^3.4.5",
     "gatsby-source-filesystem": "^2.1.9",
     "gatsby-transformer-remark": "^2.7.5",
+    "gatsby-plugin-catch-links": "^2.10.0",
     "node-fetch": "^2.6.7",
     "prismjs": "^1.20.0",
     "react": "^16.8.6",

src/docs/authoring_extensions.md

@@ -4,7 +4,7 @@ title: Authoring an Extension
 
 # Authoring Theia Extensions
 
-This guide will walk you through the process of creating Theia extensions and deploying them in your Theia-based application. Please make sure to be aware of the [different available extension mechanisms](../extensions/) of Theia (Plugins vs. Extensions) before you continue reading.
+This guide will walk you through the process of creating Theia extensions and deploying them in your Theia-based application. Please make sure to be aware of the [different available extension mechanisms](/docs/extensions/) of Theia (Plugins vs. Extensions) before you continue reading.
 
 As an example, we are going to add a menu item _Say hello_ that displays a notification "Hello world!". This article is guiding you through all the necessary steps.
 
@@ -14,7 +14,7 @@ A Theia app is composed of so-called _extensions_. An extension provides a set o
 
 Theia defines a plethora of contribution interfaces that allow extensions to add their behaviour to various aspects of the application. Just search for interfaces with the name `*Contribution` to get an idea. An extension implements the contribution interfaces belonging to the functionality it wants to deliver. In this example, we are going to implement a `CommandContribution` and a `MenuContribution`. Other ways for extensions to interact with a Theia application are via one of the various _services_ or _managers_.
 
-In Theia, everything is wired up via [dependency injection](../services_and_contributions#dependency-injection-di). An extension defines one or more dependency injection modules. This is where it binds its contribution implementations to the respective contribution interface. The modules are listed in the `package.json` of the extension package. An extension can contribute to the frontend, e.g. providing a UI extension, as well as to the backend, e.g. contributing a language server. When the application starts, the union of all these modules is used to configure a single, global dependency injection container on each, the frontend and the backend. The runtime will then collect all contributions of a specific kind by means of a multi-inject.
+In Theia, everything is wired up via [dependency injection](/docs/services_and_contributions#dependency-injection-di). An extension defines one or more dependency injection modules. This is where it binds its contribution implementations to the respective contribution interface. The modules are listed in the `package.json` of the extension package. An extension can contribute to the frontend, e.g. providing a UI extension, as well as to the backend, e.g. contributing a language server. When the application starts, the union of all these modules is used to configure a single, global dependency injection container on each, the frontend and the backend. The runtime will then collect all contributions of a specific kind by means of a multi-inject.
 
 ## Prerequisites
 

src/docs/authoring_plugins.md

@@ -4,7 +4,7 @@ title: Authoring Plug-ins
 
 # Authoring Theia Plug-ins
 
-This documentation is deprecated and needs to be updated. We currently recommend using VS Code extensions or Theia extensions instead of Theia Plugins. See the [extension overview](../extensions/) for more details.
+This documentation is deprecated and needs to be updated. We currently recommend using VS Code extensions or Theia extensions instead of Theia Plugins. See the [extension overview](/docs/extensions/) for more details.
 <!--
 Let's create our first Theia plug-in. As an example, we are going to register a command _Hello World_ that displays a notification "Hello world!". This article is guiding you through all the necessary steps.