This has been discussed before, and I would like to actually take some action on this. I don't remember what anyone said should be in them, so let's brainstorm and come up with some simple rules for the chat.
I have added a page for us to put these ideas all in one place. If you could flesh them out a bit, I can rewrite them in a more binding tone later to have them match other policies. For now we can treat it as a group project, so everyone can edit this page: