SDK is no longer preview

Author: christophwille

README.md

@@ -12,8 +12,8 @@ can be found on the [AvalonEdit homepage](http://avalonedit.net/)
 How to build
 -------
 
-AvalonEdit is targeting netcoreapp3.0, net40 and net45 TFMs. Because of netcoreapp3.0 you must have .NET Core 3.0 SDK (currently in preview) installed 
-on your machine. Visual Studio 2019 is required for working with the solution (global.json will select the proper SDK to use for building for you).
+AvalonEdit is targeting netcoreapp3.0, net40 and net45 TFMs. Because of netcoreapp3.0 you must have .NET Core 3.0 SDK installed 
+on your machine. Visual Studio 2019 16.3 and up is required for working with the solution (global.json will select the proper SDK to use for building for you).
 
 
 Documentation
@@ -36,4 +36,4 @@ Projects using AvalonEdit
 
 * https://github.com/icsharpcode/ILSpy/: .NET decompiler
 
-Note: if your project is not listed here, let us know! :)
+Note: if your project is not listed here, let us know! :)