Twitter seems to have handled adding an edit button about as well as possible. The edit button biases toward transparency, adding an edit history for every tweet and a big notice saying a tweet has been edited. Users will only have 30 minutes to edit their tweet, and will only be able to do so “a few times.” Twitter’s surely going to be looking closely at those numbers in its testing to see exactly how editable tweets should really be. It’s only coming to paying subscribers of…