Basically the title. This would help people understand the expectations set in place by moderation of said group instance, thus providing a better experience for users who join group instances only to get kicked due to a group rule they're unaware of.
Here's how i would imagine it working in the UI:
  1. Click join on a group moderated world.
  2. Ui popup with a title like "Please review the rules of the group instance before joining." followed by the rules listed on the groups page.
  3. user is provided 2 choices. "Agree and join" or "decline"
Agree and join should progress the user into the loading of the instance.
Decline should possibly include the option to "move this groups instances to the bottom of the instance list" and return the user to the instance selection ui.