Add a "Common Mistakes" pinned post

I am requesting that a common mistakes pinned post for here, #forum-feedback. I wouldn’t say there are many mistakes to make but one I can think of is trying to post in a base category like #platform-feedback instead of selecting a subcategory. Not having many mistakes probably ruins the point of the request, but having one would be nice. Maybe even the rest of the community can add some common mistakes when using the developer forum.