Moving Haddock *development* out of GHC tree

[Herbert Valerio Riedel]

On 2014-08-16 at 16:59:51 +0200, Mateusz Kowalczyk wrote:

[...]

> Herbert kindly updated the sync-all script that
> defaults to the new branch so I think we're covered. 

Minor correction: I did not touch the sync-all script at all. I merely
declared a default branch in the .gitmodules file:

  http://git.haskell.org/ghc.git/commitdiff/03a8003e5d3aec97b3a14b2d3c774aad43e0456e