The how-to tag has no tag wiki but 37 questions covering widely different topics. I'd be inclined to associate 'how to' questions with support ("How do I use Stack Exchange feature X") but users have managed to tag discussions, feature-requests and even bugs with them.
I think how-to is a meta tag, not unlike the [best-practices] tag mentioned there and should be burninated/synonymized/merged. Thoughts?
Meanwhile, the tag has been removed from a few questions and as far as I can see it's safe to apply support to the remaining ones, as @PolyGeo suggested in the answer. I can't however propose a tag synonym, that requires a ♦ moderator for a required tag: