Document :kind! in ghci built-in help

Signed-off-by: Austin Seipp <aseipp@pobox.com>

ghc/InteractiveUI.hs

@@ -246,7 +246,8 @@ defFullHelpText =
   "   :info[!] [<name> ...]       display information about the given names\n" ++
   "                               (!: do not filter instances)\n" ++
   "   :issafe [<mod>]             display safe haskell information of module <mod>\n" ++
-  "   :kind <type>                show the kind of <type>\n" ++
+  "   :kind[!] <type>             show the kind of <type>\n" ++
+  "                               (!: also print the normalised type)\n" ++
   "   :load [*]<module> ...       load module(s) and their dependents\n" ++
   "   :main [<arguments> ...]     run the main function with the given arguments\n" ++
   "   :module [+/-] [*]<mod> ...  set the context for expression evaluation\n" ++