Create dotnet/compatibility.md

This is a stand in for the currently broken URL on this page https://fable.io/docs/introduction/dotnet-users-read-this.html 
as well as the warning Fable gives when trying to run it on non-compatibly code.

Author: Recktenwald

docs/docs/dotnet/compatibility.md

@@ -0,0 +1,7 @@
+---
+title: .NET compatibility
+layout: standard
+---
+
+For compatibility with Javascrit and Typescript please see the [Javascript Compatibility](/docs/javascript/compatibility.html) section.
+For compatibility with Python see [Python Compatibility](/docs/python/compatibility.html)