Added documentation for Python Markdown Extensions

docs/setup/extensions/python-markdown-extensions.md

@@ -4,14 +4,141 @@ template: overrides/main.html
 
 # Python Markdown Extensions
 
+The [Python Markdown Extensions] package is an excellent collection of Markdown
+extensions that make technical writing a breeze. Material for MkDocs views this 
+package as a sibling of its own, which is why most provided extensions are
+already natively supported.
+
+  [Python Markdown Extensions]: https://facelessuser.github.io/pymdown-extensions/
+
 ## Supported extensions
 
+The following extensions are all supported by Material for MkDocs and therefore
+strongly recommended. See the [overview][Extensions] page for a minimal and
+recommended configuration.
+
+  [Extensions]: index.md
+
 ### Arithmatex
 
+[:octicons-workflow-24: Extension][Arithmatex] ·
+[:octicons-tag-24: 1.0.0 – present][Arithmatex support]
+
+The [Arithmatex] extension allows for rendering of block and inline equations,
+and integrates seamlessly with [MathJax][^1], a library for mathematical
+typesetting. Enable it via `mkdocs.yml`:
+
+  [^1]:
+    Other libraries like [KaTeX] are also supported and can be integrated with
+    some additional effort. See the [Arithmatex documentation on KaTeX] for
+    further guidance, as this is beyond the scope of Material for MkDocs.
+
+``` yaml
+markdown_extensions:
+  - pymdownx.arithmatex:
+      generic: true
+```
+
+Besides enabling the extension in `mkdocs.yml`, a MathJax configuration and 
+the JavaScript runtime need to be included, which can be done with a few lines
+of [additional JavaScript]:
+
+=== "`docs/javascripts/config.js`"
+
+    ``` js
+    window.MathJax = {
+      tex: {
+        inlineMath: [["\\(", "\\)"]],
+        displayMath: [["\\[", "\\]"]],
+        processEscapes: true,
+        processEnvironments: true
+      },
+      options: {
+        ignoreHtmlClass: ".*|",
+        processHtmlClass: "arithmatex"
+      }
+    };
+
+    document$.subscribe(() => {
+      MathJax.typesetPromise()
+    })
+    ```
+
+=== "`mkdocs.yml`"
+
+    ``` yaml
+    extra_javascript:
+      - javascripts/config.js
+      - https://polyfill.io/v3/polyfill.min.js?features=es6
+      - https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js
+    ```
+
+Arithmatex can be configured in many different ways, for which Material for
+MkDocs  might not provide native support. See the [Arithmatex documentation][Arithmatex] for more information.
+
+  [Arithmatex]: https://facelessuser.github.io/pymdown-extensions/extensions/arithmatex/
+  [Arithmatex support]: https://github.com/squidfunk/mkdocs-material/releases/tag/1.0.0
+  [Arithmatex documentation on KaTeX]: https://facelessuser.github.io/pymdown-extensions/extensions/arithmatex/#loading-katex
+  [MathJax]: https://www.mathjax.org/
+  [KaTeX]: https://github.com/Khan/KaTeX
+  [additional JavaScript]: ../../customization.md#additional-javascript
+
 ### Critic
 
+[:octicons-workflow-24: Extension][Critic] ·
+[:octicons-tag-24: 1.0.0 – present][Critic support]
+
+The [Critic] extension allows for the usage of [Critic Markup] to highlight
+additions, deletions or substitutions in a Markdown documents. It can be enabled
+via `mkdocs.yml`:
+
+``` yaml
+markdown_extensions:
+  - pymdownx.critic
+```
+
+The following configuration options are supported:
+
+`mode`{ #mode }
+
+:   :octicons-milestone-24: Default: `view` – This option defines how the markup 
+    should be parsed, i.e. whether to just `view` all suggest changes, or
+    alternatively `accept` or `reject` them:
+
+    === "View changes"
+
+        ``` yaml
+        markdown_extensions:
+          - pymdownx.critic:
+              mode: view
+        ```
+
+    === "Accept changes"
+
+        ``` yaml
+        markdown_extensions:
+          - pymdownx.critic:
+              mode: accept
+        ```
+
+    === "Reject changes"
+
+        ``` yaml
+        markdown_extensions:
+          - pymdownx.critic:
+              mode: reject
+        ```
+
+  [Critic]: https://facelessuser.github.io/pymdown-extensions/extensions/critic/
+  [Critic support]: https://github.com/squidfunk/mkdocs-material/releases/tag/1.0.0
+  [Critic Markup]: https://github.com/CriticMarkup/CriticMarkup-toolkit
+
 ### Details
 
+The [Details] extension supercharges the [Admonition] extension, making the
+resulting _call-outs_ collapsible, rendering
+
+
 ### Emoji
 
 ### Highlight