Add APIs

- AppRegistry
- AppState
- AsyncStorage
- Dimensions
- NativeMethods
- NetInfo
- PixelRatio
- Platform
- UIManager

docs/apis/Dimensions.md

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+# Dimensions
+
+Note: dimensions may change (e.g due to device rotation) so any rendering logic
+or styles that depend on these constants should try to call this function on
+every render, rather than caching the value.
+
+## Methods
+
+static **get**(dimension: string)
+
+Get a dimension (e.g., `"window"` or `"screen"`).
+
+Example: `const { height, width } = Dimensions.get('window')`