Fix renamed createStackNavigator to createNativeStackNavigator

Documentation was refering to `createStackNavigator` function instead of `createNativeStackNavigator`

Author: arcollector

versioned_docs/version-6.x/native-stack-navigator.md

@@ -511,41 +511,41 @@ navigation.popToTop();
 ## Example
 
 ```js
-import { createStackNavigator } from '@react-navigation/native-stack';
+import { createNativeStackNavigator } from '@react-navigation/native-stack';
 
-const Stack = createStackNavigator();
+const NativeStack = createNativeStackNavigator();
 
-function MyStack() {
+function MyNativeStack() {
   return (
-    <Stack.Navigator
+    <NativeStack.Navigator
       initialRouteName="Home"
       screenOptions={{
         headerTintColor: 'white',
         headerStyle: { backgroundColor: 'tomato' },
       }}
     >
-      <Stack.Screen
+      <NativeStack.Screen
         name="Home"
         component={Home}
         options={{
           title: 'Awesome app',
         }}
       />
-      <Stack.Screen
+      <NativeStack.Screen
         name="Profile"
         component={Profile}
         options={{
           title: 'My profile',
         }}
       />
-      <Stack.Screen
+      <NativeStack.Screen
         name="Settings"
         component={Settings}
         options={{
           gestureEnabled: false,
         }}
       />
-    </Stack.Navigator>
+    </NativeStack.Navigator>
   );
 }
 ```