Blazor virtualization state changes (#19954)

Author: guardrex

aspnetcore/blazor/components/virtualization.md

@@ -5,7 +5,7 @@ description: Learn how to use component virtualization in ASP.NET Core Blazor ap
 monikerRange: '>= aspnetcore-3.1'
 ms.author: riande
 ms.custom: mvc
-ms.date: 09/16/2020
+ms.date: 09/21/2020
 no-loc: ["ASP.NET Core Identity", cookie, Cookie, Blazor, "Blazor Server", "Blazor WebAssembly", "Identity", "Let's Encrypt", Razor, SignalR]
 uid: blazor/components/virtualization
 ---
@@ -153,3 +153,7 @@ For example, a grid or list that renders hundreds of rows containing components
 * `FetchData` component ([`Pages/FetchData.razor`](https://github.com/aspnet/samples/blob/master/samples/aspnetcore/blazor/Virtualization/Pages/FetchData.razor)): Uses the `Virtualize` component to display 25 rows of weather data at a time.
 
 ::: moniker-end
+
+## State changes
+
+When making changes to items rendered by the `Virtualize` component, call <xref:Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged%2A> to force re-evaluation and rerendering of the component.