Documented Blazor routing.

docs/en/UI/Blazor/Routing.md

@@ -1,3 +1,24 @@
 # Blazor UI: Routing
 
-TODO
+Blazor has its own [routing system](https://docs.microsoft.com/en-us/aspnet/core/blazor/fundamentals/routing) and you can use it in your applications. ABP doesn't add any new feature to it, except one small improvement for the [modular development](../../Module-Development-Basics.md).
+
+## AbpRouterOptions
+
+Blazor `Router` component requires to define `AdditionalAssemblies` when you have components in assemblies/projects other than the main application's entrance assembly. So, if you want to create razor class libraries as ABP modules, you typically want to add the module's assembly to the `AdditionalAssemblies`. In this case, you need to add your module's assembly to the `AbpRouterOptions`.
+
+**Example**
+
+````csharp
+Configure<AbpRouterOptions>(options =>
+{
+    options.AdditionalAssemblies.Add(typeof(MyBlazorModule).Assembly);
+});
+````
+
+Write this code in the `ConfigureServices` method of your [module](../../Module-Development-Basics.md).
+
+`AbpRouterOptions` has another property, `AppAssembly`, which should be the entrance assembly of the application and typically set in the final application's module. If you've created your solution with the [application startup template](../../Startup-Templates/Application.md), it is already configured for you.
+
+## See Also
+
+* [Blazor Routing](https://docs.microsoft.com/en-us/aspnet/core/blazor/fundamentals/routing) (Microsoft Documentation)

docs/en/docs-nav.json

@@ -708,6 +708,10 @@
             {
               "text": "Global Scripts & Styles",
               "path": "UI/Blazor/Global-Scripts-Styles.md"
+            },
+            {
+              "text": "Routing",
+              "path": "UI/Blazor/Routing.md"
             }
           ]
         },