Update Navigation.md

Summary:
NavigatorIOS push method arg is route object.
For working this image animation,
add passProps property to NavigationIOS,
changed _onForward function navigator.push method arg is route object

<!--
Thank you for sending the PR!

If you changed any code, please provide us with clear instructions on how you verified your changes work. In other words, a test plan is *required*. Bonus points for screenshots and videos!

Please read the Contribution Guidelines at https://github.com/facebook/react-native/blob/master/CONTRIBUTING.md to learn more about contributing to React Native.

Happy contributing!
-->
Closes https://github.com/facebook/react-native/pull/15178

Differential Revision: D5481399

Pulled By: hramos

fbshipit-source-id: b131ef27b70fc0bbc4f519a924187c19dca73ed2

docs/Navigation.md

@@ -99,6 +99,7 @@ export default class NavigatorIOSApp extends React.Component {
         initialRoute={{
           component: MyScene,
           title: 'My Initial Scene',
+          passProps: {index: 1},
         }}
         style={{flex: 1}}
       />
@@ -108,7 +109,9 @@ export default class NavigatorIOSApp extends React.Component {
 
 class MyScene extends React.Component {
   static propTypes = {
-    title: PropTypes.string.isRequired,
+    route: PropTypes.shape({
+      title: PropTypes.string.isRequired
+    }),
     navigator: PropTypes.object.isRequired,
   }
 
@@ -118,8 +121,11 @@ class MyScene extends React.Component {
   }
   
   _onForward() {
+    let nextIndex = ++this.props.index;
     this.props.navigator.push({
+      component: MyScene,
       title: 'Scene ' + nextIndex,
+      passProps: {index: nextIndex}
     });
   }