chore(changelogs): add top-level for changelogs

Author: slack

mkdocs.yml

@@ -82,6 +82,7 @@ pages:
     - Controller API v2.0: reference-guide/controller-api/v2.0.md
     - Controller API v2.1: reference-guide/controller-api/v2.1.md
     - Controller API v2.2: reference-guide/controller-api/v2.2.md
+  - Changelogs:
 theme_dir: themes/deis
 docs_dir: src
 markdown_extensions: