I'm realizing that I need to specify: I'm not primarily interested in documenting APIs, more things like:

* Preferred way of doing X

* X domain uses these tables and works like this

* This is what X feature does and here's what it looks like

Most of us work in the single large codebase, and we don't have a good separation of responsibility between the pieces yet (it's a work in progress) so for now I mostly want to document what stuff exists rather than formal API documentation.