docrails is a branch of Ruby on Rails with public write access where anyone can push doc fixes.
If you see a typo, you'd like to correct a factual error, complement some existing documentation, add a useful example... before docrails existed you had to open a pull request (or the equivalent in those days) and follow the ordinary workflow to get it accepted. docrails allows you to clone the repo, edit, and push. Done!
What is allowed in docrails?
You can freely push changes to any RDoc, guides, and READMEs.
No code can be touched at all. That's a hard rule. No matter how insignificant, not even a one character typo in a string literal.
CHANGELOGs cannot be edited either.