docs: Fix `fileSize` to say it's always included (#1883)
docs: Fix `fileSize` to say it's always included (#1883)

See discussion:
  https://github.com/react-native-image-picker/react-native-image-picker/commit/502c73e3d284c470d2009109f09bc2d71553d88b#r61280696
marcshilling/react-native-image-picker,marcshilling/react-native-image-picker,marcshilling/react-native-image-picker,marcshilling/react-native-image-picker