Add a breaking changes section to the changelog

[TheSavior]

This PR is based on https://github.com/react-native-community/releases/pull/152 and thus includes those changes as well. Once that is merged this will get simplified

This command now includes a breaking changes section

$ yarn generate -b 8c7ec519812c570535912c45dd81db51ba2fdd31 -c bdd1a675ba6949868d11ef0c3dccaa8f336ca384

## [bdd1a675ba6949868d11ef0c3dccaa8f336ca384.0]

### Breaking

- Animated: Remove `defaultProps` Parameter ([a70987c](https://github.com/facebook/react-native/commit/a70987c) by [@yungsters](https://github.com/yungsters))
- Remove TextInput's `inputView` prop ([1804e7c](https://github.com/facebook/react-native/commit/1804e7c) by [@TheSavior](https://github.com/TheSavior))
- Changelog: [General] [Changed] Split NativeImageLoader into NativeImageLoaderAndroid and NativeImageLoaderIOS ([d37baa7](https://github.com/facebook/react-native/commit/d37baa7) by [@ejanzer](https://github.com/ejanzer))
- Removing <TextInput>'s `onTextInput` event ([3f7e0a2](https://github.com/facebook/react-native/commit/3f7e0a2) by [@shergin](https://github.com/shergin))

#### Android specific

#### iOS specific

### Added

- [General][Changed] TextInput no longer does an extra round trip to native on focus/blur ([e9b4928](https://github.com/facebook/react-native/commit/e9b4928) by [@TheSavior](https://github.com/TheSavior))
- Platform.select now supports native as an option. ([a6fc089](https://github.com/facebook/react-native/commit/a6fc089) by [@koke](https://github.com/koke))

...

[turnrye]

This is something that the community had repeatedly asked for, but I've been a bit too rigid in trying to adhere to the keep a changelog recommendations. I'm open to this change and have found other examples where a similar approach was taken, like with sensu. As such I'll move forward with this review. @thesavior thank you!

[TheSavior]

I'm thinking that the two most important parts of our release notes are 1. The highlighted changes, and 2. The breaking changes.

I think we often will need to add more text to this breaking changes section before releasing in order to share what people should do instead so having these pulled up to the top for us is valuable.

[grabbou]

We will most likely need or should provide an additional description, but at least we will not miss any breaking changes to investigate.