No docs -- but that would be a good addition. Some tips:
Stick to the GitHub model of sending pull requests.
Anyone on the Contributors team can merge PRs so feel free to review
and merge other PRs in other repos that you're interested in.
Go ahead and selfie-merge your own PRs if no one else is contributing
to that repo yet.
If people are interested in a repo they'll 'watch' it and comment and
contribute from there. The more active contributors there are for a
given repo the more collaboration and review should happen on PRs to
that repo.
Feel free to ping me (@whiteinge) or the Core team anytime.