modified changelog

Author: hkernbach

ChangeLog.md

@@ -10,6 +10,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 
 - added support for named indices
 - added minReplicationAttribute for collections and graphs
+- added batched thread support in ArangoCollection.importDocuments (by @rkhaja)
 
 ## [5.0.7] - 2019-07-19