Better documentation for setupTests.js when ejecting (#3656)
Better documentation for setupTests.js when ejecting (#3656)

* Better documentation for setupTests.js when ejecting

When running `npm run eject` before creating `src/setupTests.js`, the resulting `package.json` file, won't contain any entry for it - and this is correct in my opinion, since otherwise Jest will crash - but it's useful to have it documented and avoid pointless waste of time.

* Added additional note about src/setupTests.js

Added another note about src/setupTests.js and `npm run eject` in Testing Components section

* Update README.md

* Update README.md

peopleticker/create-react-app,romaindso/create-react-app,Clearcover/web-build,tharakawj/create-react-app,infernojs/create-inferno-app,tharakawj/create-react-app,jdcrensh/create-react-app,CodingZeal/create-react-app,lolaent/create-react-app,lolaent/create-react-app,ontruck/create-react-app,amido/create-react-app,maletor/create-react-app,ConnectedHomes/create-react-web-app,ConnectedHomes/create-react-web-app,appier/create-react-app,maletor/create-react-app,infernojs/create-inferno-app,0xaio/create-react-app,0xaio/create-react-app,GreenGremlin/create-react-app,picter/create-react-app,jdcrensh/create-react-app,IamJoseph/create-react-app,peopleticker/create-react-app,timlogemann/create-react-app,appier/create-react-app,0xaio/create-react-app,mangomint/create-react-app,mangomint/create-react-app,GreenGremlin/create-react-app,d3ce1t/create-react-app,ro-savage/create-react-app,maletor/create-react-app,peopleticker/create-react-app,ConnectedHomes/create-react-web-app,ontruck/create-react-app,Timer/create-react-app,d3ce1t/create-react-app,in2core/create-react-app,tharakawj/create-react-app,d3ce1t/create-react-app,jdcrensh/create-react-app,appier/create-react-app,picter/create-react-app,just-boris/create-preact-app,christiantinauer/create-react-app,amido/create-react-app,ConnectedHomes/create-react-web-app,IamJoseph/create-react-app,digitalorigin/create-react-app,viankakrisna/create-react-app,IamJoseph/create-react-app,mangomint/create-react-app,d3ce1t/create-react-app,brysgo/create-react-app,timlogemann/create-react-app,christiantinauer/create-react-app,digitalorigin/create-react-app,Timer/create-react-app,picter/create-react-app,mangomint/create-react-app,in2core/create-react-app,ontruck/create-react-app,g3r4n/create-esri-react-app,ro-savage/create-react-app,timlogemann/create-react-app,digitalorigin/create-react-app,GreenGremlin/create-react-app,timlogemann/create-react-app,just-boris/create-preact-app,GreenGremlin/create-react-app,g3r4n/create-esri-react-app,christiantinauer/create-react-app,CodingZeal/create-react-app,infernojs/create-inferno-app,lolaent/create-react-app,Timer/create-react-app,Clearcover/web-build,liamhu/create-react-app,in2core/create-react-app,viankakrisna/create-react-app,viankakrisna/create-react-app,brysgo/create-react-app,romaindso/create-react-app,christiantinauer/create-react-app,liamhu/create-react-app,facebookincubator/create-react-app,romaindso/create-react-app,facebookincubator/create-react-app,amido/create-react-app,jdcrensh/create-react-app,facebookincubator/create-react-app,Clearcover/web-build,CodingZeal/create-react-app,Timer/create-react-app,liamhu/create-react-app,g3r4n/create-esri-react-app,ro-savage/create-react-app,brysgo/create-react-app,just-boris/create-preact-app