Merge pull request #4872 from qbig/minor-panresponder-doc

[Doc][Android][Minor][PanResponder]add doc for native event in doc

Libraries/vendor/react/browser/eventPlugins/PanResponder.js

@@ -25,7 +25,24 @@ var currentCentroidY = TouchHistoryMath.currentCentroidY;
  * It provides a predictable wrapper of the responder handlers provided by the
  * [gesture responder system](/react-native/docs/gesture-responder-system.html).
  * For each handler, it provides a new `gestureState` object alongside the
- * normal event.
+ * native event object:
+ *
+ * ```
+ * onPanResponderMove: (event, gestureState) => {}
+ * ```
+ *
+ * A native event is a synthetic touch event with the following form:
+ *
+ *  - `nativeEvent`
+ *      + `changedTouches` - Array of all touch events that have changed since the last event
+ *      + `identifier` - The ID of the touch
+ *      + `locationX` - The X position of the touch, relative to the element
+ *      + `locationY` - The Y position of the touch, relative to the element
+ *      + `pageX` - The X position of the touch, relative to the root element
+ *      + `pageY` - The Y position of the touch, relative to the root element
+ *      + `target` - The node id of the element receiving the touch event
+ *      + `timestamp` - A time identifier for the touch, useful for velocity calculation
+ *      + `touches` - Array of all current touches on the screen
  *
  * A `gestureState` object has the following:
  *