You raise a very valid issue. Four+ years ago when I first joined MS there was a chat anteroom one had to enter prior to entering chat itself. In that anteroom was the chat guidelines and every time you logged in you were also indicating you understood the chat guidelines. During one of the site upgrades that happened nearly 3 years ago now that room and those guidelines vanished into thin air.
One of the things that I have discussed with my supervisors on the BoD is a return of that chat anteroom which will contain the chat guidelines and other pertinent information. It may take some time (months at best) to make that happen due to funding, available volunteer time, etc., but your request is heard and understood. We're going to be addressing this very issue.
"Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting 'Holy Shit! What a ride!'" ~Hunter S. Thompson