Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -4,7 +4,7 @@
 
 * The revision number of three.js
 * Tell us where did you observe the problem: your browser version, your operating system, your graphics card (for example Chrome 23.0.1271.95, Windows 7, Nvidia Quadro 2000M)
-* If you can, try to check your problem on multiple browsers / multiple computers (if you are on Windows, especially helpful is to compare ANGLE and OpenGL renderers)
+* If you can, try to check your problem on multiple browsers / multiple computers (if you are on Windows, especially helpful is to [compare ANGLE and OpenGL renderers](https://github.com/mrdoob/three.js/wiki/How-to-use-OpenGL-or-ANGLE-rendering-on-Windows))
 * Identify the problem. Saying ,It doesn't work, doesn't help much.
 * A small testcase. (Big chance is that when you do this, you'll find the answer yourself.)
 * What did you try already??