Add mailgun link to readme
Add mailgun link to readme

LucasKA/mail-builder,porkepic/ccube-email-templates,andrebellafronte/grunt-email-workflow,kuzin/EmailGen,leemunroe/grunt-email-workflow,Xerasset/grunt-email-code,vukanac/grunt-email-workflow,cyponthemic/performance-email-future-proof-template,Xerasset/grunt-email-code,aisensiy/benz_email1,timripley/grunt-email-workflow,Mizpah/NSTransEmails,serjiosilent/grunt-email-design,19peaches/grunt-email-workflow,iamchathu/grunt-email-workflow,Ye-Ting/email-flow,johndavidsparrow/grunt-email-workflow,clecompte/grunt-email-design,vukanac/grunt-email-workflow,serjiosilent/grunt-email-design,juliusakula/grunt-email-workflow,Traff1kMike/grunt-email,jasonmelgoza/grunt-email-design,jasonmelgoza/grunt-email-design,timripley/grunt-email-workflow,brightbytes/email-templater,juliusakula/grunt-email-workflow,newswim/geekemail,andrebellafronte/grunt-email-workflow,Ye-Ting/email-flow,taeo/grunt-email-design,Traff1kMike/grunt-email,johndavidsparrow/grunt-email-workflow,taeo/grunt-email-design,Webstars/the-weekly,newswim/geekemail,brightbytes/email-templater,rightscale-design/grunt-email-workflow,kuzin/EmailGen,porkepic/ccube-email-templates,leemunroe/grunt-email-workflow,19peaches/grunt-email-workflow,Mizpah/NSTransEmails,LucasKA/mail-builder,iamchathu/grunt-email-workflow,sherzberg/grunt-email-workflow,rightscale-design/grunt-email-workflow