Added Open Graph and Twitter cards documentation

docs/setup/adding-a-comment-system.md

@@ -34,6 +34,23 @@ This will insert a comment system on _every page, except the index page_.
   [3]: https://www.mkdocs.org/user-guide/configuration/#site_url
   [4]: https://help.disqus.com/en/articles/1717111-what-s-a-shortname
 
+### Metadata
+
+The [Metadata][5] extension, which is part of the standard Markdown library,
+adds the ability to add [front matter][6] to a document and can be enabled via
+`mkdocs.yml`:
+
+``` yaml
+markdown_extensions:
+  - meta
+```
+
+Front matter is written as a series of key-value pairs at the beginning of the
+Markdown document, delimited by a blank line which ends the YAML context.
+
+  [5]: https://github.com/squidfunk/mkdocs-material/blob/master/src/base.html
+  [6]: https://jekyllrb.com/docs/front-matter/
+
 ## Customization
 
 ### Selective integration
@@ -41,7 +58,7 @@ This will insert a comment system on _every page, except the index page_.
 [:octicons-file-code-24: Source][2] ·
 :octicons-mortar-board-24: Difficulty: _easy_
 
-If the [Metadata][5] extension is enabled, you can disable or enable Disqus for
+If the [Metadata][7] extension is enabled, you can disable or enable Disqus for
 specific pages by adding the following to the front matter of a page:
 
 === "Enable Disqus"
@@ -60,4 +77,4 @@ specific pages by adding the following to the front matter of a page:
     ---
     ```
 
-  [5]: ../reference/meta-tags.md#metadata
+  [7]: #metadata

docs/setup/changing-the-colors.md

@@ -230,6 +230,16 @@ in the [color schemes][10] section:
   --md-primary-fg-color--light: #ECB7B7;
   --md-primary-fg-color--dark:  #90030C;
 }
+```
+
+Additionally, the `slate` color scheme defines all of it's colors via `hsla`
+color functions and deduces its colors from the `--md-hue` CSS variable. You
+can tune the `slate` theme with:
+
+``` css
+[data-md-color-scheme="slate"] {
+  --md-hue: 210; /* [0, 360] */
+}
 ```
 
   [9]: https://www.w3.org/TR/selectors-4/#attribute-selectors

docs/setup/changing-the-language.md

@@ -142,7 +142,7 @@ want to change in the [base translation][1] and add it to the partial.
 
 Let's say you want to change "__Table of contents__" to "__On this page__":
 
-``` jinja
+``` html
 {% macro t(key) %}{{ {
   "toc.title": "On this page"
 }[key] }}{% endmacro %}

docs/setup/setting-up-site-analytics.md

@@ -54,9 +54,9 @@ In order to integrate another analytics service provider offering an
 asynchronous JavaScript-based tracking solution, you can [extend the theme][5]
 and [override the `analytics` block][6]:
 
-``` jinja
+``` html
 {% block analytics %}
-  {# Add custom analytics integration here #}
+  <!-- Add custom analytics integration here -->
 {% endblock %}
 ```
 

docs/setup/setting-up-site-search.md

@@ -212,7 +212,7 @@ template, both of which don't transform the query prior to submission, or
 customize the `transform` function, you can do this by [overriding the 
 `config` block][14]:
 
-``` jinja
+``` html
 {% block config %}
   <script>
     var search = {
@@ -241,7 +241,7 @@ want to switch the web worker with your own implementation, e.g. to submit
 search to an external service, you can add a custom JavaScript file to the `docs`
 directory and [override the `config` block][14]:
 
-``` jinja
+``` html
 {% block config %}
   <script>
     var search = {