docs: add example to MD2 demo

Author: corvinsz

src/MainDemo.Wpf/Domain/MainWindowViewModel.cs

@@ -237,7 +237,8 @@ private static IEnumerable<DemoItem> GenerateDemoItems(ISnackbarMessageQueue sna
             [
                 DocumentationLink.DemoPageLink<Typography>(),
                 DocumentationLink.StyleLink("TextBlock")
-            ])
+            ],
+            new TypographyViewModel())
         {
             HorizontalScrollBarVisibilityRequirement = ScrollBarVisibility.Auto
         };