Summary:
The text that appears on screen is in App.js component.
The project that is being generated using react-native shows `To get started, edit App.js` text when run, but the documentation says to edit index.js file. The text is actually present in App.js, therefore the app is correct, but the documentation is not.
[DOCS] [ENHANCEMENT] [GettingStarted.md] - Wrong name of the file to edit
Closes https://github.com/facebook/react-native/pull/16550
Differential Revision: D6184953
Pulled By: shergin
fbshipit-source-id: c7385a349de8983aff80af8b393b3a973b4ef5cf