patch applied (packages/mtl): we can have documentation on instances now, so use it

[Simon Marlow]

Thu Jul  1 08:41:32 PDT 2010  Simon Marlow <marlowsd at gmail.com>
  * we can have documentation on instances now, so use it

    M ./Control/Monad/Error.hs +4

View patch online:
http://darcs.haskell.org/cgi-bin/darcsweb.cgi?r=packages/mtl;a=darcs_commitdiff;h=20100701154132-12142-0279a73c4af9c1bcce16f685e25a68a0c8036536.gz