Awsome! So awsome!
So, will the new dungeons be incorporated into official releases, or will they work as a plug-in? As in, we post our dungeons here and everyone can pick what they like and add it into their game, or we post and playtest, then put it into new release for everyone?
The intention is to incorporate the dungeons into official releases. This will attract players, and perhaps some developers. This means you can create full-length dungeons and be confident that they will continue to appear in continuing development.
I would say, the most direct/guru way would be to fork the git repository and you can work on your own dungeon in your own fork, commit, push changes to your remote, and then pull request the changes into attnam/master. However, as I write this I can see that with the status quo there might be long times between releases. I feel that there will be more frequent releases as dungeons reach the cut-and-polish stage.
You will want players to play test your dungeons as soon as you make changes. The players don't use github, that much is obvious. But I would recommend you use github as the vehicle of ultimate authorship, because it will enable you to show the work was yours, and help you track changes etc. It also means I can see it if you get stuck, or if there is a bug. When you feel the code is ready you can make a pull request, I can merge this into the main line and do a release. In this way it will be released to the general public.
For all github's technical usefulness, it will not get you the rapid feedback you require. The forum here is a good development nucleus with plenty of the game's legendary power players who drop in on us from time to time. When I did CLIVAN I found lots of people coming out of the woodwork to push my dungeons to their limits and the feedback was awesome! They smashed through everything and found all the loopholes, which was embarrassing, but humbling that people took the time out to review my work.
I expect if you get a thread going on the forum here you will get some eager followers. As you develop, attach your dungeon data files here and explain where they go so people can test it out. If you don't want to use git (the learning curve can seem steep, I'll admit) and you start out in this way, then that is fine too. You can even jump into github right at the end and push all the changes in one go. I know you already have a fork though...
The first part will be to flesh the thing out using your imagination, and writing the dungeon script (or copy-pasting a lot and changing things). It will be a lot of solitary hours, keep a notebook handy, graph paper is good too.