add upgrade and compatibility notes to README for country select for #1060
add upgrade and compatibility notes to README for country select for #1060

mikz/formtastic,EndingChaung/formtastic,ConferenceCloud/formtastic,paulodiovani/formtastic,justinfrench/formtastic,thenthen8515/formtastic,nishaya/formtastic,ConferenceCloud/formtastic,Guestfolio/formtastic,ryanfox1985/formtastic,EndingChaung/formtastic,nishaya/formtastic,Guestfolio/formtastic,thenthen8515/formtastic,sideci-sample/sideci-sample-formtastic,paulodiovani/formtastic,ryanfox1985/formtastic,justinfrench/formtastic,ryanfox1985/formtastic,Davidzhu001/formtastic,justinfrench/formtastic,mikz/formtastic,Davidzhu001/formtastic