I think it'd be significantly better to mod the game to display the default controls (correct for everybody except those hardcore enough to know how to edit a .cfg file, and those people probably don't need it), than the current state (correct for exactly nobody, other than those who went to the effort of re-configuring the game to its original controls).
And I assume if you can hack in mouselook, you can hack that text.
Wait a couple months. Someone will probably make a mod for this (or include this change in an existing mod). =)
Also, I had to smile at the phrase "hardcore enough to know how to edit a .cfg file". A file with the .cfg extension is literally nothing more than a text file, and can be opened with any text editor such as Notepad (or even a proper word processor, such as WordPad or Word). I think pretty much anyone who played PC games in the '90s or before had to
figure this kind of stuff out as a matter of course. Editing a .CFG or .INI file was about on the same level as using DOS...which was required to play most games. I would be the last person to describe myself as "hardcore" as either a gamer or a computer user, but I can muddle through these sorts of things. Besides, these days, we have the Internet to help out! ;)