Document multiple build environments via `env-cmd` #4071 (#4117)
Document multiple build environments via `env-cmd` #4071 (#4117)

* Docs - Document multiple build environments via

* Docs - Document multiple build environments via

* Docs - Document multiple build environments via

* Docs - Document multiple build environments via env-cmd

* fix - based upon requests

* Update README.md

viankakrisna/create-react-app,d3ce1t/create-react-app,facebookincubator/create-react-app,mangomint/create-react-app,facebookincubator/create-react-app,GreenGremlin/create-react-app,infernojs/create-inferno-app,d3ce1t/create-react-app,jdcrensh/create-react-app,Timer/create-react-app,ConnectedHomes/create-react-web-app,jdcrensh/create-react-app,jdcrensh/create-react-app,timlogemann/create-react-app,ConnectedHomes/create-react-web-app,ConnectedHomes/create-react-web-app,infernojs/create-inferno-app,viankakrisna/create-react-app,Timer/create-react-app,Timer/create-react-app,mangomint/create-react-app,GreenGremlin/create-react-app,ConnectedHomes/create-react-web-app,timlogemann/create-react-app,IamJoseph/create-react-app,mangomint/create-react-app,viankakrisna/create-react-app,IamJoseph/create-react-app,timlogemann/create-react-app,GreenGremlin/create-react-app,Timer/create-react-app,timlogemann/create-react-app,mangomint/create-react-app,infernojs/create-inferno-app,d3ce1t/create-react-app,jdcrensh/create-react-app,facebookincubator/create-react-app,IamJoseph/create-react-app,GreenGremlin/create-react-app,d3ce1t/create-react-app