Slight doc typos

Section 7.4 of the User Guide (or doc source
ghc/docs/user_guide/glasgow_exts.sgml) references "Haskell 1.4" several
times when "Haskell 98" would perhaps be more appropriate.

Also, section 7.4.10 ("Arbitrary-rank polymorphism", same sgml source)
has an example with functions f1, g1, f2, g2 and f3, but a few
paragraphs later a non-existent g3 is mentioned twice.

                                                           /L/e/k/t/u