Update src/Service/Athena/CHANGELOG.md

Author: jderusse

src/Service/Athena/CHANGELOG.md

@@ -5,7 +5,7 @@
 ### Added
 
 - AWS api-change: Add FEDERATED type to CreateDataCatalog. This creates Athena Data Catalog, AWS Lambda connector, and AWS Glue connection. Create/DeleteDataCatalog returns DataCatalog. Add Status, ConnectionType, and Error to DataCatalog and DataCatalogSummary. Add DeleteCatalogOnly to delete Athena Catalog only.
-- AWS api-change: TODO
+- AWS api-change: Added `ap-southeast-5` region
 
 ## 3.0.0