Document linking Haskell wrapper when building from source

[dmjio]

Currently the installation instructions for arrayfire-haskell target users who install binaries into /lib / lib64 on OSX/ Linux respectively. For "power users" (those who build from source), there should be instructions on how to install.

cabal configure -f-disable-default-paths --extra-lib-dirs=/path/to/arrayfire/lib --extra-include-dirs=/path/to/arrayfire/include