ScrollView zoom is not supported on Android (#851)

See facebook#20154

docs/using-a-scrollview.md

@@ -59,6 +59,6 @@ AppRegistry.registerComponent(
 
 ScrollViews can be configured to allow paging through views using swiping gestures by using the `pagingEnabled` props. Swiping horizontally between views can also be implemented on Android using the [ViewPagerAndroid](viewpagerandroid.md) component.
 
-A ScrollView with a single item can be used to allow the user to zoom content. Set up the `maximumZoomScale` and `minimumZoomScale` props and your user will be able to use pinch and expand gestures to zoom in and out.
+On iOS a ScrollView with a single item can be used to allow the user to zoom content. Set up the `maximumZoomScale` and `minimumZoomScale` props and your user will be able to use pinch and expand gestures to zoom in and out.
 
 The ScrollView works best to present a small amount of things of a limited size. All the elements and views of a `ScrollView` are rendered, even if they are not currently shown on the screen. If you have a long list of more items than can fit on the screen, you should use a `FlatList` instead. So let's [learn about list views](using-a-listview.md) next.