Add Marginalia link to the Developer Guide (#39937)

docs/developers-guide/start.md

@@ -23,6 +23,7 @@ This guide contains detailed information on how to work on Metabase codebase.
 - [How to work with the frontend code](frontend.md)
 - [How to add support in Metabase for other languages](internationalization.md)
 - [Working with Clojure](clojure.md)
+- [Annotated Clojure source code](https://metabase-dev-docs.github.io/)
 
 ## Testing