Update CHANGELOG to reflect the changes in build 1.5.2.

CHANGELOG.md

@@ -13,6 +13,14 @@
 
 ---
 
+# 1.5.2
+
+## aframe-ar.js
+- aframe-ar.js - `<a-marker>` elements will emit `markerFound` and `markerLost` events, if they have `emitevents='true'` set.
+
+## Demos
+- Created [an example](https://jeromeetienne.github.io/AR.js/aframe/examples/marker-events.html) that demonstrates emitting events when markers are found and lost, and registering the respective event listeners.
+
 # 1.5.1
 
 ## aframe-ar.js