Update README to clarify that you need .NET Core 1.0 RTM

Author: SteveSandersonMS

README.md

@@ -20,7 +20,7 @@ This repo contains:
  * A Yeoman generator that creates preconfigured app starting points ([guide](http://blog.stevensanderson.com/2016/05/02/angular2-react-knockout-apps-on-aspnet-core/))
  * Samples and docs
 
-Everything here is cross-platform, and works with .NET Core 1.0 RC2 or later on Windows, Linux, or OS X.
+Everything here is cross-platform, and works with .NET Core 1.0 (RTM) or later on Windows, Linux, or OS X.
 
 ## Creating new applications