patch applied (packages/Cabal): Add a HACKING file

[Simon Marlow]

Sat Aug 22 08:16:36 PDT 2009  Duncan Coutts <duncan at haskell.org>
  * Add a HACKING file
  Ignore-this: 222a83edbe3bf27574bfe51df7f109f0
  Seems people do not know that the source guide exists.

    A ./HACKING

View patch online:
http://darcs.haskell.org/packages/Cabal/_darcs/patches/20090822151636-adfee-6c24647bd1e1e0a57871ad1efa43a8c20d011de5.gz