Recommended .gitignore for react-native

I'm trying out react native and ejected into a full build environment. Sadly, the eject-script did not create a sensible .gitignore file.

Not knowing a lot about app-development, I wonder what directories I could .gitignore here?

I'm guessing:

• android/build
• android/app/build
• android/.gradle/

Are these alright, or are there any more directories I should .gitignore?