React Native : 0.41 app.json

That's used for the new react-native eject command. As stated in the RN source code:

The eject command re-creates the android and ios native folders. Because native code can be difficult to maintain, this new script allows an app.json to be defined for the project, which is used to configure the native app. The app.json config may contain the following keys:

• name - The short name used for the project, should be TitleCase
• displayName - The app's name on the home screen

Feel free to check the source

Since I don't plan to eject I removed the app.json File (just to have less files flying around at root level). App still works as expected.