Reference: #13
By default, the generator expects to be running in the root provider directory. The new `provider-dir` flag enables developers to run the command in any directory where the relative or absolute path is passed in as the base directory for all file operations for a provider codebase. All prior behaviors should be preserved, such as customizing via other flags like `examples-dir`.
Due to lack of existing end-to-end testing (known technical debt), verified by locally compiling and running against existing HashiCorp-owned provider implementations which use `tfplugindocs` and by running the command in a subdirectory of hashicorp/terraform-provider-tls which has a mixture of custom and default templates and observed no changes or errors:
```console
$ tfplugindocs generate -provider-dir=..
rendering website for provider "terraform-provider-tls" (as "terraform-provider-tls")
copying any existing content to tmp dir
exporting schema from Terraform
compiling provider "tls"
using Terraform CLI binary from PATH if available, otherwise downloading latest Terraform CLI binary
running terraform init
getting provider schema
rendering missing docs
generating missing resource content
resource "tls_locally_signed_cert" template exists, skipping
resource "tls_private_key" template exists, skipping
resource "tls_self_signed_cert" template exists, skipping
resource "tls_cert_request" template exists, skipping
generating missing data source content
resource "tls_certificate" template exists, skipping
generating template for "tls_public_key"
generating missing provider content
provider "terraform-provider-tls" template exists, skipping
rendering static website
cleaning rendered website dir
rendering templated website to static markdown
rendering "data-sources/certificate.md.tmpl"
rendering "data-sources/public_key.md.tmpl"
rendering "index.md.tmpl"
rendering "resources/cert_request.md.tmpl"
rendering "resources/locally_signed_cert.md.tmpl"
rendering "resources/private_key.md.tmpl"
rendering "resources/self_signed_cert.md.tmpl"
```