Now that I know about the wiki posts, this is my opinion and workaround (obviously it is just my opinion) I would prefer a separate wiki page for documenting of UM purposes than forum threads because it makes it look more formal and you can create a wiki page as an index.
This way documentation would have topics like “Installing UM”, “Troubleshooting”, “Known issues”, “Configuring UM” while tutorials that tend to took like “non official stuff” would go to the forum in a wiki post, e.g. “make UM look like Mac OS”, “Rotate images with GIMP using Caja’s context menu”.
A workaround may be make a wiki post as an index page (forum wiki page) and add there the links to the tutorials/official documentation and also to make the tutorials (as documentation topic) look more formal shuldn’t have responses and of course should be wikis.