fix typo

Former-commit-id: 185f5314e01d31412a995ed0a6dc479b88d34b12

CHANGELOG.md

@@ -26,7 +26,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-653 - When config check fail, Milvus close without message
 - MS-654 - Describe index timeout when building index
 - MS-658 - Fix SQ8 Hybrid can't search
-- #20 - C++ sdk example get grpc error 
+- \#20 - C++ sdk example get grpc error 
 
 ## Improvement
 - MS-552 - Add and change the easylogging library