DOCSP-16034 csharp vs compat (#739)

* DOCSP-16034: add visual studio compatibility notice

Author: Chris Cho

source/csharp.txt

@@ -87,5 +87,13 @@ Language Compatibility
 
 .. include:: /includes/about-driver-compatibility.rst
 
+Visual Studio Compatibility
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If your Visual Studio IDE project depends on the official Mongo C# driver
+version 2.10 or later, you must use
+`Visual Studio 2017 <https://docs.microsoft.com/en-us/visualstudio/releasenotes/vs2017-relnotes>`__
+or later.
+
 .. include:: /includes/help-links-csharp.rst