improve os x install instructions
improve os x install instructions

haskell-infra/hl,kxxoling/hl,imalsogreg/hl,gbaz/hl,snoyberg/hl,josefs/hl,haskell-lang/haskell-lang,imalsogreg/hl,josefs/hl,haskell-infra/hl,snoyberg/hl,snoyberg/hl,bitemyapp/commercialhaskell.com,gbaz/hl,haskell-lang/haskell-lang,haskell-infra/hl,josefs/hl,bitemyapp/commercialhaskell.com,haskell-lang/haskell-lang,erantapaa/hl,kxxoling/hl,erantapaa/hl,bitemyapp/commercialhaskell.com,gbaz/hl,commercialhaskell/commercialhaskell.com,imalsogreg/hl,commercialhaskell/commercialhaskell.com,erantapaa/hl,kxxoling/hl,commercialhaskell/commercialhaskell.com