adding a 'Getting started' section to the README
adding a 'Getting started' section to the README

HubSpot/premailer,sendwithus/premailer,peterbe/premailer,graingert/premailer,ionelmc/premailer,peterbe/premailer,peterbe/premailer,BlokeOne/premailer-1,kengruven/premailer,industrydive/premailer,lavr/premailer,BlokeOne/premailer-1,sendwithus/premailer,lavr/premailer,kengruven/premailer,graingert/premailer,ionelmc/premailer,industrydive/premailer