add changelog

Former-commit-id: a6bdcf1ea83451136f9ab1cb8535b358a27ddc0e

cpp/CHANGELOG.md

@@ -27,6 +27,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-45 - Implement DeleteTable interface
 - MS-75 - cmake: change faiss version to 1.5.2; add CUDA gencode
 - MS-81 - fix faiss ptx issue; change cuda gencode
+- MS-84 - cmake: add arrow, jemalloc and jsoncons third party; default build option OFF
 
 ## Task
 - MS-74 - Change README.md in cpp