README: Mention F4 instead of the custom error jump key bindings
README: Mention F4 instead of the custom error jump key bindings

tomv564/SublimeHaskell,hcarvalhoalves/SublimeHaskell,Bodigrim/SublimeHaskell,bscottm/SublimeHaskell,SublimeHaskell/SublimeHaskell,bscottm/SublimeHaskell,kgadek/SublimeHaskell,hcarvalhoalves/SublimeHaskell,kgadek/SublimeHaskell,SublimeHaskell/SublimeHaskell,tomv564/SublimeHaskell,Bodigrim/SublimeHaskell