On both the about page it is explained how the site works. To my eyes, this should include that a user asking question should edit his post to improve it if some other users are asking clarification or to provide more information.
Even in the help area on asking, there's nothing about that either! This results in loads of new users trying to post comments to include more information.
So, could we either (or preferably both):
Include a topic on the help page on asking, e.g.:
Someone asks for more information in a comment. Should I reply or edit my question?
On a Q&A site it's a convention that you include all information in the question body rather than posting information in comments. It is also not needed to put a new section "update" in your question body, as we can see that you've edited your question. Your question will also appear on top of the "Active" list again.
Include a short section on improving a question or how to handle comments.