Added documentation for pulling the Insiders Docker image

docs/getting-started.md

@@ -41,7 +41,7 @@ Material for MkDocs always strives to support the latest versions, so there's
 no need to install those packages separately.
 
 _Note that in order to install [Material for MkDocs Insiders][8], you'll
-need to [become a sponsor][9], create a [personal access token][10][^1], and
+need to [become a sponsor][9], create a personal access token[^1], and
 set the_ `GH_TOKEN` _environment variable to the token's value._
 
   [5]: https://python-markdown.github.io/
@@ -49,17 +49,25 @@ set the_ `GH_TOKEN` _environment variable to the token's value._
   [7]: https://facelessuser.github.io/pymdown-extensions/
   [8]: insiders.md
   [9]: insiders.md#how-to-become-a-sponsor
-  [10]: https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token
 
 ### with docker
 
-The official [Docker image][11] is a great way to get up and running in a few
+The official [Docker image][10] is a great way to get up and running in a few
 minutes, as it comes with all dependencies pre-installed. Pull the image for the 
 `latest` version with:
 
-```
-docker pull squidfunk/mkdocs-material
-```
+=== "Material for MkDocs"
+
+    ```
+    docker pull squidfunk/mkdocs-material
+    ```
+
+=== "Insiders"
+
+    ```
+    docker login -u ${GH_USERNAME} -p ${GH_TOKEN} ghcr.io
+    docker pull ghcr.io/squidfunk/mkdocs-material-insiders
+    ```
 
 The `mkdocs` executable is provided as an entry point and `serve` is the 
 default command. If you're not familiar with Docker don't worry, we have you
@@ -67,12 +75,16 @@ covered in the following sections.
 
 The following plugins are bundled with the Docker image:
 
-- [mkdocs-minify-plugin][12]
-- [mkdocs-redirects][13]
+- [mkdocs-minify-plugin][11]
+- [mkdocs-redirects][12]
 
-  [11]: https://hub.docker.com/r/squidfunk/mkdocs-material/
-  [12]: https://github.com/byrnereese/mkdocs-minify-plugin
-  [13]: https://github.com/datarobot/mkdocs-redirects
+_Note that in order to install [Material for MkDocs Insiders][8], you'll
+need to [become a sponsor][9], create a personal access token[^2], and
+set the_ `GH_TOKEN` _environment variable to the token's value._
+
+  [10]: https://hub.docker.com/r/squidfunk/mkdocs-material/
+  [11]: https://github.com/byrnereese/mkdocs-minify-plugin
+  [12]: https://github.com/datarobot/mkdocs-redirects
 
 ??? question "How can I add plugins to the Docker image?"
 
@@ -96,7 +108,7 @@ The following plugins are bundled with the Docker image:
 
 ### with git
 
-Material for MkDocs can be directly used from [GitHub][14] by cloning the
+Material for MkDocs can be directly used from [GitHub][13] by cloning the
 repository into a subfolder of your project root which might be useful if you
 want to use the very latest version:
 
@@ -122,15 +134,25 @@ pip install -r mkdocs-material/requirements.txt
 _Note that in order to install [Material for MkDocs Insiders][8], you'll
 need to [become a sponsor][9]._
 
-  [14]: https://github.com/squidfunk/mkdocs-material
+  [13]: https://github.com/squidfunk/mkdocs-material
 
   [^1]:
     In order to use `pip` to install from the private repository over HTTPS, the
-    personal access token requires the [`repo`][15] scope. The creation and
-    usage of an access token is only necessary when installing Insiders over
-    HTTPS, which is the recommended way when building from within a CI/CD
+    [personal access token][14] requires the [`repo`][15] scope. The creation
+    and usage of an access token is only necessary when installing Insiders
+    over HTTPS, which is the recommended way when building from within a CI/CD
     workflow, e.g. using [GitHub Pages][16] or [GitLab Pages][17].
 
+  [^2]:
+    If you want to use `docker` to pull the private Docker image from the
+    [GitHub Container Registry][18], the [personal access token][14] requires
+    the [`read:packages`][15] scope. Note that you need to login before pulling
+    the Docker image. As an example, see the [`publish`][19] workflow of the
+    Material for MkDocs repository.
+
+  [14]: https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token
   [15]: https://docs.github.com/en/developers/apps/scopes-for-oauth-apps#available-scopes
   [16]: publishing-your-site.md#github-pages
   [17]: publishing-your-site.md#gitlab-pages
+  [18]: https://docs.github.com/en/free-pro-team@latest/packages/getting-started-with-github-container-registry/about-github-container-registry
+  [19]: https://github.com/squidfunk/mkdocs-material/blob/master/.github/workflows/publish.yml#L72-L77