added an about page

lib/pages/main_navigation_scaffold.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 
+import 'about_page.dart';
 import 'landing_page.dart';
 import 'map_page.dart';
 
@@ -23,6 +24,16 @@ class _MainNavigationScaffoldState extends State<MainNavigationScaffold> {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
+      appBar: AppBar(
+        title: Text('Floodwatch'),
+        actions: [
+          IconButton(
+            onPressed: () =>
+                Navigator.of(context).pushNamed(AboutPage.routeName),
+            icon: Icon(Icons.info_outline),
+          )
+        ],
+      ),
       bottomNavigationBar: NavigationBar(
         selectedIndex: _selectedPageIndex,
         onDestinationSelected: (value) => setState(() {