How do I request re-opening a question that was placed "on hold"?
Now that you've edited it, it should automatically enter the reopen review queue for people to look at. It is then up to reviewers to decide if they want to vote to reopen (VTRO). People (with at least 3k reputation) can also VTRO directly from the question, if they come across it.
To add to, not supplant, Scimonster's excellent answer:
You can comment on the question with an
@-ping for whoever closed the question to draw the revision thereof to his or her attention. This may be rude if the question was closed by votes (after all, it was closed by random passersby or a queue, so let it be reopened thereby also), but I think is wholly appropriate if it was moderator-closed.