Highlight that GHCP migration support for framework apps is in preview (#48685)

* Highlight that GHCP migration support for framework apps is in preview

* Fix broken link

* change warning to note

* Update docs/core/porting/github-copilot-app-modernization-overview.md

* Revise .NET upgrade notes and emphasize ASP.NET migration

Updated notes on .NET Framework upgrade scenarios and added emphasis on ASP.NET project migration recommendations.

---------

Co-authored-by: Andy (Steve) De George <[email protected]>

Author: twsouthwick

docs/core/porting/github-copilot-app-modernization-overview.md

@@ -56,25 +56,30 @@ To start an upgrade or migration, interact with GitHub Copilot, following these
 
 The modernization agent supports upgrading projects coded in C#. The following types of projects are supported:
 
-- ASP.NET and ASP.NET Core (including related technologies such as MVC, Razor Pages, and Web API)
+- ASP.NET Core (and related technologies such as MVC, Razor Pages, and Web API)
 - Blazor
 - Azure Functions
 - Windows Presentation Foundation
 - Windows Forms
 - Class libraries
 - Console apps
 
+> [!IMPORTANT]
+> .NET Framework upgrade scenarios are currently in preview, which includes technologies such as Windows Forms for .NET Framework and ASP.NET. Using the modernization agent to design an upgrade plan might work in limited scenarios. If upgrading an ASP.NET project (or related technologies such as MVC, Razor Pages, Web API) see [ASP.NET Migration](/aspnet/core/migration/fx-to-core) for recommendations.
+
 To learn how to start an upgrade, see [How to upgrade a .NET app with GitHub Copilot app modernization](how-to-upgrade-with-github-copilot.md).
 
 ### Upgrade paths
 
 The following upgrade paths are supported:
 
 - Upgrade projects from older .NET versions to the latest.
-- Upgrade projects from .NET Framework to the latest version of .NET.
 - Modernize your code base with new features.
 - Migrate components and services to Azure.
 
+> [!IMPORTANT]
+> Upgrading projects from .NET Framework to the latest version of .NET is still in preview.
+
 ## Migrate .NET projects to Azure
 
 The modernization agent combines automated analysis, AI-driven code remediation, build and vulnerability checks, and deployment automation to simplify migrations to Azure. The following capabilities describe how the agent assesses readiness, applies fixes, and streamlines the migration process: