feat: add basic nesting example

example/StackNavigator.tsx

@@ -10,6 +10,7 @@ import {
 
 type Props = {
   initialRouteName?: string;
+  navigation?: NavigationProp;
   children: React.ReactElement[];
 };
 
@@ -42,6 +43,7 @@ const StackRouter = {
     switch (action.type) {
       case 'PUSH':
         return {
+          ...state,
           index: state.index + 1,
           routes: [
             ...state.routes,
@@ -54,6 +56,7 @@ const StackRouter = {
       case 'POP':
         return state.index > 0
           ? {
+              ...state,
               index: state.index - 1,
               routes: state.routes.slice(0, state.routes.length - 1),
             }
@@ -73,13 +76,10 @@ const StackRouter = {
   },
 };
 
-export default function StackNavigator({ initialRouteName, children }: Props) {
+export default function StackNavigator(props: Props) {
   // The `navigation` object contains the navigation state and some helpers (e.g. push, pop)
   // The `descriptors` object contains `navigation` objects for children routes and helper for rendering a screen
-  const { navigation, descriptors } = useNavigationBuilder(StackRouter, {
-    initialRouteName,
-    children,
-  });
+  const { navigation, descriptors } = useNavigationBuilder(StackRouter, props);
 
   return (
     <div style={{ position: 'relative' }}>