adds default exporting of App (facebook#424)

bgerhards · charpeni · commit 3e73402d7c60 · 2018-06-27T12:00:39.000-04:00
diff --git a/docs/navigation.md b/docs/navigation.md
@@ -32,6 +32,8 @@ const App = createStackNavigator({
   Home: { screen: HomeScreen },
   Profile: { screen: ProfileScreen },
 });
+
+export default App;
 ```
 
 Each screen component can set navigation options such as the header title. It can use action creators on the `navigation` prop to link to other screens:
