Fix typo in man page.
Fix typo in man page.

Original patch is a Erik de Castro Lopo's darcs patch.
I ported that to git repository.
  http://trac.haskell.org/haskell-platform/ticket/172

  Fix typo in man page.
  Erik de Castro Lopo <erikd@mega-nerd.com>**20110417092403
    Ignore-this: eebb3c99f7eaeef0370d26e6b37763a3

alanz/Alex,simonmar/alex,Teino1978-Corp/Teino1978-Corp-alex,hvr/alex,simonmar/alex,beni55/alex,sol/alex,beni55/alex,alanz/Alex,hvr/alex,Teino1978-Corp/Teino1978-Corp-alex,sol/alex