update changelog

Former-commit-id: 9aefaa8682dbe383b7fdf75b4edeb6332bf36019

cpp/CHANGELOG.md

@@ -8,6 +8,7 @@ Please mark all change in change log and use the ticket from JIRA.
 
 ## Improvement
 - MS-552 - Add and change the easylogging library
+- MS-553 - Refine cache code
 
 ## New Feature