GitHub seems to recommend that projects should include a "code of conduct" — they even provide handy templates. However, the two that are currently on offer seem a bit officious and heavy-handed.
I'd quote Wil Wheaton on this. However, while the sentiment is correct and nicely to the point, some people might not like its specific wording. Suffice it to say, "we're all adults here, please act like it." Translation, "hatefully childish behavior won't be tolerated."
No time has been specifically allocated to this project's contents nor allocated to their support. Project contents are provided "as is" - so, "buyer beware". Try to be nice and we'll try to return the behavior. Contribute or otherwise help us improve the project and we'll try to figure out (in all of the copious time that's been preallocated to this project) a way to send you a virtual beer.