Like all open source projects, BuddyPress is a community effort. Anyone can add to the documentation–the Codex–by visiting this BP link and creating a new Codex article, or adding to and/or editing an existing one.
Your help in documenting BuddyPress will be appreciated!
I would like to add my vote to fleshing out the docs. Having comprehensive docs (at least for template tags) could have saved people like me hours and hours of work. And sad to say, the sparse documentation is pretty much the only thing that’s keeping me from embracing BuddyPress again for my next social networking project…
As for contributing, I’m only semi-literate in how BuddyPress works but I’ll try to contribute what I can based on what I’ve learned digging through the code. If only there was a way. Why isnt there a wiki or something?
codex.buddypress.org – if you’re logged into buddypress.org, you should be able to edit any page on the codex.
Yeah… I’m logged in and don’t see any edit buttons. 
It’s at the very bottom left and is available as you scroll. You don’t see that?
Alternatively, go into https://codex.buddypress.org/wp-admin/ and find the Pages that way.
