Added links for third edition

Author: josdirksen

README.md

@@ -1,6 +1,14 @@
 learning-threejs
 ================
 
-Branch used to update all examples to three.js release r63
+## Second edition learning Three.js
+
+The examples in this branch are based on r63 and correspond to the second edition of "Learning Three.js"
+
+## Third edition Learning Three.js
+
+Currently I'm in progress of converting all the examples to the latest (r88 as of now) of Three.js for the
+ third edition of "Learning Three.js", if you want to follow the progress check the following repository:
+
+https://github.com/josdirksen/learning-threejs-third/
 
-Code repository for the examples from the Packt book "Learning Threejs"