Update submodule git branch for haddock
Update submodule git branch for haddock

This is meta-information is used by commands such as e.g.

  git submodule update --remote util/haddock

[skip ci]

nathyong/microghc-ghc,forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc,nathyong/microghc-ghc,nathyong/microghc-ghc,forked-upstream-packages-for-ghcjs/ghc,nathyong/microghc-ghc,forked-upstream-packages-for-ghcjs/ghc,nathyong/microghc-ghc,nathyong/microghc-ghc,forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc,nathyong/microghc-ghc