MapStaticAssets to migration /2

Author: Rick-Anderson

aspnetcore/migration/80-90.md

@@ -70,6 +70,22 @@ In the project file, update each [`Microsoft.AspNetCore.*`](https://www.nuget.or
 </ItemGroup>
 ```
 
+## Replace UseStaticFiles with MapStaticAssets
+
+Blazor has different update instructions than Razor Pages and ASP.NET Core MVC.
+
+### Blazor
+
+* Replace [UseStaticFiles](/dotnet/api/microsoft.aspnetcore.builder.staticfileextensions.usestaticfiles) with [MapStaticAssets](/dotnet/api/microsoft.aspnetcore.builder.staticassetsendpointroutebuilderextensions.mapstaticassets) in `Program.cs`
+* Update explicit references to static assets in .razor files to use the `@Assets["asset-path"]` API. This should ***NOT*** be done for the Blazor framework scripts (`*blazor.\*.js*`)
+* Update the root `App.razor` component to include the `<ImportMap />` component in the head.
+
+### Razor Pages and ASP.NET Core MVC
+
+* Replace [UseStaticFiles](/dotnet/api/microsoft.aspnetcore.builder.staticfileextensions.usestaticfiles) with [MapStaticAssets](/dotnet/api/microsoft.aspnetcore.builder.staticassetsendpointroutebuilderextensions.mapstaticassets) in `Program.cs`
+* Chain a call to `.WithStaticAssets` after `MapRazorPages` or `MapControllerRoute` in `Program.cs`. For an example, see the <xref:fundamentals/static-files?view=aspnetcore-9.0&preserve-view=true>
+* Add `<script type="importmap"></script>` to the head of the main layout file.
+
 ## Blazor
 
 [!INCLUDE[](~/migration/80-to-90/includes/blazor.md)]