Summary:
This PR seeks to improve the documentation of PushNotificationIOS.
The method didReceiveRemoteNotification without a fetch completion handler is deprecated by Apple and they [discourage using it](https://developer.apple.com/reference/uikit/uiapplicationdelegate/1623117-application) in favor of the [version with the handler](https://developer.apple.com/reference/uikit/uiapplicationdelegate/1623013-application).
Reasons for this change:
1. Our docs say that this method is required for remote notifications, but it's not. (It's one of possibilities with a recommendation not to use it.)
2. The method is deprecated by Apple and people shouldn't use it.
3. If you use the deprecated method, in 99% of the cases it will behave in a different way from what you'd expect. In particular, you won't get remote notifications when your app is in the background.
As there's no benefit (as far as I know) of using the method, I don't think we should even mention it to the users.
This is a re-opened PR that was mis
Closes https://github.com/facebook/react-native/pull/11109
Differential Revision: D4232800
Pulled By: javache
fbshipit-source-id: d3b509db41a549aa7fbc41753c648085df43d8ee
9c7952d9e1