I had the same question and one of the Discord moderators told me that you can only submit a game once unless there's some game breaking issue preventing it from working. I'm not entirely sure where he gets this, because I set up my project page before submitting and I still have the option to edit the downloadable files.
So I guess you can....? I'd let somebody know before you do it, of course, but you might be able to add an HTML version after the fact.
(PlugN'Play)