Add flexbox details to readme
Add flexbox details to readme

OC-2057

crhistianr/angular-buyer,Four51SteveDavis/JohnsonBros,Four51SteveDavis/JohnsonBros,crhistianr/angular-buyer,Four51/demo_buyer,Four51/demo_buyer,spencerwalker/angular-buyer,ordercloud-api/angular-buyer,spencerwalker/angular-buyer,ordercloud-api/angular-buyer