improve usage info

[guest]

Claus Reinke suggests:

also, could the usage info (runhaskell Setup --help) please be amended?
something like the two extra lines on usage cycle and home page below.

claus

------------------------------------------------------------------------------
$ runhaskell.exe Setup.lhs --help
Usage: Setup.lhs [GLOBAL FLAGS]
  or:  Setup.lhs COMMAND [FLAGS]

Global flags:
  -h, -?  --help  Show this help text

+Typical usage cycle:  1. configure  2. build  3. install
+
Commands:
  configure     Prepare to build the package.
  build         Make this package ready for installation.
  clean         Clean up after a build.
  install       Copy the files into the install locations. Run register.
  copy          Copy the files into the install locations.
  sdist         Generate a source distribution file (.tar.gz or .zip).
  test          Run the test suite, if any (configure with UserHooks).
  haddock       Generate Haddock HTML code from Exposed-Modules.
  pfe           Generate Programatica Project.
  register      Register this package with the compiler.
  unregister    Unregister this package with the compiler.

For more information about a command, try 'Setup.lhs COMMAND --help'.
+
+This Setup feature has been prepared using the Haskell Cabal infrastructure.
+See http://haskell.org/cabal/ for more information.
------------------------------------------------------------------------------

[guest]

Fix description

[ijones]

I just checked in a fix for this request. Good idea :)