We're approaching release!
We have put an extended description on the WIKI page for the Forum Addon and will slowly be adding how-to information. Before release, we hope to have all the basics covered.
There is only one known release-blocking code change to be made which will hopefully be completed in the next few hours.
In any event - you can read more info about the Addon and why it was created at the Wiki. [ DM42 Hubzilla Addons ] Main - Addon:Forum