Update Changelog.md

Changelog.md

@@ -2,6 +2,9 @@
 
 All notable changes to this project will be documented in this file.
 
+## [0.53] - 2020-09-23
+- DBOARD-328: fixed improper response when router is unknown
+
 ## [0.52] - 2020-09-07
 - POL1-228 (and others):
   - allow /poller/interfaces to be called without an argument