Document GitHub Copilot app modernization for migration

Added information about the GitHub Copilot app modernization extension for upgrading ASP.NET Framework applications to ASP.NET Core.

Author: wadepickett

aspnetcore/migration/fx-to-core/tooling.md

@@ -10,6 +10,7 @@ uid: migration/fx-to-core/tooling
 # Use tooling to help migrate ASP.NET Framework to ASP.NET Core
 
 ## The GitHub Copilot app modernization
+
 To upgrade ASP.NET Framework applications (MVC, Web API, and Web Forms) to ASP.NET Core, use the [GitHub Copilot app modernization Visual Studio extension](/dotnet/core/porting/github-copilot-app-modernization/overview).
 
 The GitHub Copilot app modernization agent is a Visual Studio extension that leverages AI to simplify the process of upgrading legacy .NET applications. By integrating with GitHub Copilot Chat, this tool analyzes your solution to generate upgrade plans and assists in rewriting code to support ASP.NET Core. It streamlines the migration workflow by reducing manual effort, identifying dependencies, and providing interactive, automated guidance for modernizing your codebase. To learn how to upgrade your ASP.NET apps using the recommended tooling, see [How to upgrade a .NET app with GitHub Copilot app modernization](/dotnet/core/porting/github-copilot-app-modernization/how-to-upgrade-with-github-copilot).