Add pointer to Poly Toolkit

Change-Id: If002be1988b457c9c07620697f2d55cba841fa9c

README.md

@@ -1,14 +1,14 @@
 # Tilt Brush Toolkit
 
-The Tilt Brush Toolkit is a collection of scripts and assets that allow you to use [Tilt Brush](http://g.co/tiltbrush) data in your creative projects.
+The Tilt Brush Toolkit is a collection of scripts and assets that allow you to use [Tilt Brush](http://g.co/tiltbrush) data in your creative projects. If you simply want to import Tilt Brush geometry into Unity, this package is mostly superseded by [Poly Toolkit](https://github.com/googlevr/poly-toolkit-unity).
 
 ## Contents
 
 ### Unity SDK
 
 ![Unity SDK](http://i.imgur.com/UdJg4Tz.gif)
 
-Scripts, shaders and tools for importing and manipulating Tilt Brush  sketches in [Unity](http://unity3d.com/)
+Scripts, shaders and tools for importing and manipulating Tilt Brush .fbx exports in [Unity](http://unity3d.com/). Unless you specifically need to use .fbx -- for instance, because Maya is part of your workflow -- try Poly Toolkit first.
 
 * Easily import sketches into Unity
 * Brush shaders and materials