Added back changelog and upgrade instructions

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

@@ -1,3 +1,7 @@
+---
+template: overrides/main.html
+---
+
 # Adding a comment system
 
 Material for MkDocs is natively integrated with [Disqus][1], a comment system
@@ -9,10 +13,43 @@ integrated, too.
 
 ## Configuration
 
-### Comment system
+### Disqus
 
+First, ensure you've set [`site_url`][2] in `mkdocs.yml`. Then, to integrate
+Material for MkDocs with [Disqus][1], create an account and a site giving you a
+[shortname][3], and add it to `mkdocs.yml`:
 
+``` yaml
+extra:
+  disqus: <shortname>
+```
+
+This will insert a comment system on _every page, except the index page_.
+
+  [2]: https://www.mkdocs.org/user-guide/configuration/#site_url
+  [3]: https://help.disqus.com/en/articles/1717111-what-s-a-shortname
 
 ## Customization
 
 ### Selective integration
+
+If the [Metadata][4] 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"
+
+    ``` markdown
+    ---
+    disqus: <shortname>
+    ---
+    ```
+
+=== "Disable Disqus"
+
+    ``` markdown
+    ---
+    disqus: ""
+    ---
+    ```
+
+  [4]: ../reference/meta-tags.md#metadata

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

@@ -31,7 +31,7 @@ google_analytics:
   [3]: https://github.com/squidfunk/mkdocs-material/blob/master/src/partials/integrations/analytics.html
   [4]: https://support.google.com/analytics/answer/1042508
 
-### Tracking site search
+#### Enabling site search tracking
 
 Besides basic page views, _site search_ can also be tracked to better understand
 how people use your documentation and what they expect to find. To enable