Update adding-typescript.md (#7815)
Update adding-typescript.md (#7815)


d3ce1t/create-react-app,d3ce1t/create-react-app,jdcrensh/create-react-app,Timer/create-react-app,facebookincubator/create-react-app,facebookincubator/create-react-app,facebookincubator/create-react-app,Timer/create-react-app,Timer/create-react-app,Timer/create-react-app,jdcrensh/create-react-app,jdcrensh/create-react-app,d3ce1t/create-react-app,jdcrensh/create-react-app,d3ce1t/create-react-app