update changelog entry

Author: cognifloyd

CHANGELOG.rst

@@ -14,6 +14,7 @@ Added
   working on StackStorm, improve our security posture, and improve CI reliability thanks in part
   to pants' use of PEX lockfiles. This is not a user-facing addition.
   #5778 #5789 #5817 #5795 #5830 #5833 #5834 #5841 #5840 #5838 #5842 #5837 #5849 #5850
+  #5846
   Contributed by @cognifloyd
 
 * Added a joint index to solve the problem of slow mongo queries for scheduled executions. #5805