Fixes "guesture" typo in PanResponser docs

Summary:
Simple typo fix in docs.
Closes https://github.com/facebook/react-native/pull/13247

Differential Revision: D4819135

Pulled By: ericvicenti

fbshipit-source-id: 64bc597133a31276fdff8f1ef2ee061f2a9bb17d

Libraries/Interaction/PanResponder.js

@@ -77,7 +77,7 @@ const currentCentroidY = TouchHistoryMath.currentCentroidY;
  *       onMoveShouldSetPanResponderCapture: (evt, gestureState) => true,
  *
  *       onPanResponderGrant: (evt, gestureState) => {
- *         // The guesture has started. Show visual feedback so the user knows
+ *         // The gesture has started. Show visual feedback so the user knows
  *         // what is happening!
  *
  *         // gestureState.d{x,y} will be set to zero now