Fix the demo page so adding custom notes works on the web version. (#1134)

Co-authored-by: Austin Stoker <austin@austinstoker.com>

example/lib/pages/home_page.dart

@@ -223,8 +223,10 @@ class _HomePageState extends State<HomePage> {
                   null),
               sizeSmall: const TextStyle(fontSize: 9),
             ),
-          embedBuilders: defaultEmbedBuildersWeb,
-        ),
+            embedBuilders: [
+              ...defaultEmbedBuildersWeb,
+              NotesEmbedBuilder(addEditNote: _addEditNote),
+            ]),
       );
     }
     var toolbar = QuillToolbar.basic(