update changelog

Author: djih

CHANGELOG.md

@@ -1,12 +1,10 @@
 ## Unreleased
 
-<<<<<<< HEAD
-* Add initial_referrer and initial_referring_domain user properties, which persist the initial referrer for the duration of the user's session.
-=======
+* Initial_referrer is captured as a setOnce, and referrer is only updated once per session; it is no longer sent with every event.
+
 ## 2.6.2 (November 17, 2015)
 
 * Fix bug where response code is not passed to XDomainRequest callback (affects IE versions 10 and lower).
->>>>>>> origin/master
 
 ## 2.6.1 (November 6, 2015)