We're in the midst of transitioning from our Wiki over to Sphinx-based documentation. We just completed it this weekend, have a look:
We'd love contributors to it, anything from how-to's for plugins or themes to guides for administrating NodeBB from an end-user perspective.
It's part of our core repository. The idea is that we can update docs concurrently along with the core (ex. if I were to add a new plugin hook, I would also update the documentation at the same time). Hopefully we can also increase participation as well.
Anyways, give us your thoughts. If you want a certain section included or if you were interested in contributing to something, let us know