Finish implementing send page

flutter/lib/pages/settings/root.dart

@@ -11,7 +11,7 @@ class _SettingsRootPageState extends State<SettingsRootPage> {
   @override
   Widget build(BuildContext context) {
     return Center(
-      child: Text('Settings'),
+      child: Text('(coming soon...)'), //TODO
     );
   }
 }