Added Uno-specific readme updates.

README.md

@@ -1,3 +1,9 @@
+# Uno Platform port of MVVM Light Toolkit
+
+This port allows for [Uno-based apps](http://platform.uno) to use the MVVM Light Toolkit on Windows, iOS, Android and WebAssembly.
+
+The [Uno.GalaSoft.MvvmLight.Platform](https://www.nuget.org/packages/Uno.GalaSoft.MvvmLight.Platform/) and [Uno.GalaSoft.MvvmLight](https://www.nuget.org/packages/Uno.GalaSoft.MvvmLight/) Nuget packages is available.
+
 # MVVM Light Toolkit
 
 The main purpose of the toolkit is to accelerate the creation and development of MVVM applications in Xamarin.Android, Xamarin.iOS, Xamarin.Forms, Windows 10 UWP, Windows Presentation Foundation (WPF), Silverlight, Windows Phone.