remove redundant message in Tavern now that mod names are styled 

Do not merge until https://github.com/HabitRPG/habitrpg/pull/3825 is merged.

This PR removes the text "Moderators' names are always highlighted in orange or purple" from the message that appears above the Tavern chat. See the screenshots in https://github.com/HabitRPG/habitrpg/pull/3825