In [[Special:Userrights]], the Message [[MediaWiki:editing]] is being used to
indicate which User's groups/rights are to be modified. This message is already
used when Articles are edited. There is no way for correct a wording matching both
cases. Also, ther is no way, to inclde a correct ling on $1 for both uses.
Consequentially, there should be a message on its own for [[Special:Userrights]]