Thats a good idea, it can be hard to wade through masses of comments asking questions that are answered on the addons main page, and that's just as a user, not an author trying to keep an eye on the comments for their addons.
Something more "hit you on the head" would be handy to reduce the numbers of posts from people who think it's easier/quicker to post a question and wait for an answer than read a few lines of text.
The fileinfo page is getting a redesign very soon and that space will no longer be there. However a notice box above the comments is a good idea and can be added with out much trouble.