add link to extensions architecture discussion to docs

Author: lukepistrol

Sources/CodeEditKit/Documentation.docc/Documentation.md

@@ -4,4 +4,6 @@ CodeEditKit is a dynamic library which is shared between CodeEdit and it's exten
 
 ## Overview
 
-This is still work in progress.
+This is still work in progress. 
+
+> See [this thread](https://github.com/orgs/CodeEditApp/discussions/792) for more information.