Apply code fencing to Router element in example (#14954)

aspnetcore/blazor/routing.md

@@ -5,7 +5,7 @@ description: Learn how to route requests in apps and about the NavLink component
 monikerRange: '>= aspnetcore-3.0'
 ms.author: riande
 ms.custom: mvc
-ms.date: 09/23/2019
+ms.date: 10/09/2019
 uid: blazor/routing
 ---
 # ASP.NET Core Blazor routing
@@ -79,11 +79,13 @@ The content of `<NotFound>` tags can include arbitrary items, such as other inte
 
 Use the `AdditionalAssemblies` parameter to specify additional assemblies for the `Router` component to consider when searching for routable components. Specified assemblies are considered in addition to the `AppAssembly`-specified assembly. In the following example, `Component1` is a routable component defined in a referenced class library. The following `AdditionalAssemblies` example results in routing support for `Component1`:
 
+```cshtml
 <Router
     AppAssembly="typeof(Program).Assembly"
     AdditionalAssemblies="new[] { typeof(Component1).Assembly }>
     ...
 </Router>
+```
 
 ## Route parameters