Tweaks to the template for P4. (#6635)

packages/flutter_tools/templates/create/lib/main.dart.tmpl

@@ -29,7 +29,7 @@ class MyApp extends StatelessWidget {
         // reset back to zero -- the application is not restarted.
         primarySwatch: Colors.blue,
       ),
-      home: new MyHomePage(title: 'Flutter Demo'),
+      home: new MyHomePage(title: 'Flutter Demo Home Page'),
     );
   }
 }
@@ -71,6 +71,10 @@ class _MyHomePageState extends State<MyHomePage> {
   Widget build(BuildContext context) {
     // This method is rerun every time setState is called, for instance
     // as done by the _incrementCounter method above.
+    // The Flutter framework has been optimized to make rerunning
+    // build methods fast, so that you can just rebuild anything that
+    // needs updating rather than having to individually change
+    // instances of widgets.
     return new Scaffold(
       appBar: new AppBar(
         // Here we take the value from the MyHomePage object that