Docs: Add API style/casing rule (#19627)

* Docs: Update Centrify Section In Generic Oauth Ref #18207

* Docs: Alphabetise Features / Data Sources (#19289)

* Docs: Add Title Case rule for API names (#19620)

* Update contribute/style-guides/documentation-style-guide.md

wfm, thanks!

Co-Authored-By: Marcus Olsson <olsson.e.marcus@gmail.com>

contribute/style-guides/documentation-style-guide.md

@@ -55,6 +55,7 @@ For all items not covered in this guide, refer to the [Microsoft Style Guide](ht
 ### Capitalization
 
 * Grafana, Loki, and Prometheus are always capitalized unless part of a code block.
+* API names are always Title Case, followed by "API"—for example, "Dashboard Permissions API"
 * Git is always capitalized, unless part of a code block.
 * Abbreviations are always capitalized (such as API, HTTP, ID, JSON, SQL, or URL) unless they are part of a code block.