Update contrib documentation (#53504)

The PR #53138 moved us to using .NET 6 Preview 3 but did not update our
documentation. Historically moving to new .NET SDK versions was manual
process and we "knew" to update the docs when we updated the version.
Now though it's flowing automatically via arcade and we missed it.

Short term this will get the docs in line with the requirements. Longer
term though working on a way to make sure automation doesn't silently
break our docs here.

docs/contributing/Building, Debugging, and Testing on Windows.md

@@ -17,10 +17,10 @@ The minimal required version of .NET Framework is 4.7.2.
 
 1. [Visual Studio 2019 16.9](https://visualstudio.microsoft.com/downloads/)
     - Ensure C#, VB, MSBuild, .NET Core and Visual Studio Extensibility are included in the selected work loads
-    - Ensure Visual Studio is on Version "16.8" or greater
+    - Ensure Visual Studio is on Version "16.9" or greater
     - Ensure "Use previews of the .NET Core SDK" is checked in Tools -> Options -> Environment -> Preview Features
     - Restart Visual Studio
-1. [.NET 6.0 Preview 1 SDK](https://dotnet.microsoft.com/download/dotnet-core/6.0) [Windows x64 installer](https://dotnet.microsoft.com/download/dotnet/thank-you/sdk-6.0.100-preview.1-windows-x64-installer)
+1. [.NET 6.0 Preview 3 SDK](https://dotnet.microsoft.com/download/dotnet-core/6.0) [Windows x64 installer](https://dotnet.microsoft.com/download/dotnet/thank-you/sdk-6.0.100-preview.3-windows-x64-installer)
 1. [PowerShell 5.0 or newer](https://docs.microsoft.com/en-us/powershell/scripting/setup/installing-windows-powershell). If you are on Windows 10, you are fine; you'll only need to upgrade if you're on earlier versions of Windows. The download link is under the ["Upgrading existing Windows PowerShell"](https://docs.microsoft.com/en-us/powershell/scripting/install/installing-windows-powershell?view=powershell-6#upgrading-existing-windows-powershell) heading.
 1. Run Restore.cmd
 1. Open Roslyn.sln