added comments and refactored code

lib/pages/main_navigation_scaffold.dart

@@ -5,6 +5,7 @@ import 'map_page.dart';
 
 class MainNavigationScaffold extends StatefulWidget {
   const MainNavigationScaffold({super.key});
+
   static const routeName = '/';
 
   @override
@@ -12,13 +13,13 @@ class MainNavigationScaffold extends StatefulWidget {
 }
 
 class _MainNavigationScaffoldState extends State<MainNavigationScaffold> {
-  int _selectedPageIndex = 0;
-
   final List<Widget> _pages = [
     const LandingPage(),
     const MapPage(),
   ];
 
+  int _selectedPageIndex = 0;
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -32,6 +33,7 @@ class _MainNavigationScaffoldState extends State<MainNavigationScaffold> {
           NavigationDestination(icon: Icon(Icons.map_outlined), label: 'Map'),
         ],
       ),
+      // Used IndexedStack to save the page state while navigating
       body: IndexedStack(
         index: _selectedPageIndex,
         children: _pages,