update whatsnu

what's new.md

@@ -26,6 +26,7 @@
 - Complete rework of Unity3D exporter. [Documentation](http://doc.babylonjs.com/resources/intro) ([MackeyK24](https://github.com/MackeyK24))
 - Introducing the BabylonJS viewer, an HTML-based 3D/model viewer, with Babylon at its core. [Documentation](http://doc.babylonjs.com/extensions/the_babylon_viewer) ([RaananW](https://github.com/RaananW))
 - Full NPM support for BabylonJS and its modules, based on UMD and including Typings. [BabylonJS on npm](https://www.npmjs.com/~babylonjs) ([RaananW](https://github.com/RaananW))
+- Viewer upgrade - see [PR](https://github.com/BabylonJS/Babylon.js/pull/4160) ([RaananW](https://github.com/RaananW))
 
 ## Updates