Better comment for the default manageHook

Config.hs

@@ -79,7 +79,8 @@ manageHook w _ _ c | c `elem` floats = fmap (W.float w . snd) (floatLocation w)
 manageHook w _ n _ | n `elem` ignore = reveal w >> return (W.delete w)
  where ignore = ["gnome-panel", "desktop_window", "kicker", "kdesktop"]
 
--- The default rule, do not edit this line.
+-- The default rule: return the WindowSet unmodified.  You typically do not
+-- want to modify this line.
 manageHook _ _ _ _ = return id
 
 -- |