User manual improvments
User manual improvments

- Document that you can use 'forall' in instance decls

- Change the sections a bit, so that big sections (like
  lexically scoped type variables, pattern synonyms,
  implicit parameters) become more visible

GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc