baffling manual sections

[Jason Dusek]

  I'm a little puzzled by these seeming duplicate pages in the
  manual:

    http://www.haskell.org/ghc/dist/current/docs/users_guide/type-extensions.html

    http://www.haskell.org/ghc/dist/current/docs/users_guide/data-type-extensions.html

  They give slightly different section numbers to similar stuff.
  The former page also has a curious discussion of standalone
  deriving with a `for` keyword:

    http://www.haskell.org/ghc/dist/current/docs/users_guide/type-extensions.html#stand-alone-deriving

--
Jason Dusek