add discussiosn to p3 (#9274)

Author: jamesmontemagno

release-notes/9.0/preview/preview3/README.md

@@ -16,6 +16,15 @@
 
 Instructions on getting started with .NET 9 can be found in the [getting started guide](../../get-started.md). Installers and binaries for .NET 9 Preview 3 can be found [here on GitHub](./9.0.0-preview.3.md). 
 
+## Announcements & Discussions
+
+Discuss this release with the product teams on GitHub through the announcements for this release. 
+
+* [.NET MAUI](https://github.com/dotnet/maui/discussions/21783) 
+* [ASP.NET Core](https://github.com/dotnet/aspnetcore/discussions/55086)
+* [Libraries & Runtime](https://github.com/dotnet/runtime/discussions/100928) 
+* [Containers](https://github.com/dotnet/dotnet-docker/discussions/5351)
+* [Source-build](https://github.com/dotnet/source-build/discussions/4320)
 
 ## Stay up-to-date
 
@@ -26,4 +35,4 @@ You can find a detailed overview of all new features in .NET 9:
 * [What's new in .NET MAUI](https://learn.microsoft.com/dotnet/maui/whats-new/dotnet-9)
 * [What's new in EF Core](https://learn.microsoft.com/ef/core/what-is-new/ef-core-9.0/whatsnew)
 
-The latest .NET 9 release is always available at [dotnet.microsoft.com](https://dotnet.microsoft.com/download/dotnet/9.0) and [.NET 9 Releases](../../README.md).
+The latest .NET 9 release is always available at [dotnet.microsoft.com](https://dotnet.microsoft.com/download/dotnet/9.0) and [.NET 9 Releases](../../README.md).