Add link to ReactJS.NET on server-side environments page (#6607)

docs/09.3-environments.md

@@ -29,6 +29,11 @@ If you use JSX, you may want to pre-compile your components. Alternatively you m
 >
 > Some versions of Node.js have an `Object.assign` implementation that does not preserve key order. This can cause errors when validating the markup, creating a warning that says "React attempted to reuse markup in a container but the checksum was invalid". If you run into this issue, you can override `Object.assign` to use a polyfill that preserves key order. For more details, see [Issue #6451](https://github.com/facebook/react/issues/6451).
 
+C#
+==
+
+Support for server-side component rendering and JSX compilation (via Babel) in a .NET Framework / ASP.NET environment is provided through our [ReactJS.NET](http://reactjs.net/) project.
+
 
 ## Nashorn