clarify installation procedure
clarify installation procedure

refs:
https://github.com/pyllyukko/user.js/issues/173
https://developer.mozilla.org/en-US/Firefox/Enterprise_deployment
Mac OS paths are still missing
pyllyukko/user.js,Toromtomtom/user.js,nodiscc/user.js,nodiscc/user.js,pyllyukko/user.js,Toromtomtom/user.js