Update setting-up-your-editor.md (#8247)
Update setting-up-your-editor.md (#8247)

`Auto Fix is enabled by default. Use the single string form.` warning is shown in `.vscode/settings.json` due to changes in vscode-eslint. 
As autoFix is set to default, object format in `eslint.validate` is deprecated.
d3ce1t/create-react-app,Timer/create-react-app,Timer/create-react-app,facebookincubator/create-react-app,jdcrensh/create-react-app,facebookincubator/create-react-app,facebookincubator/create-react-app,jdcrensh/create-react-app,d3ce1t/create-react-app,jdcrensh/create-react-app,Timer/create-react-app,jdcrensh/create-react-app,d3ce1t/create-react-app,d3ce1t/create-react-app,Timer/create-react-app