docs: updates changelog

Author: nunomaduro

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## Fixed
 
 - additional `clear`, `delete` & `deleteObject` types for the `.batch` method ([#1149](https://github.com/algolia/algoliasearch-client-javascript/pull/1149))
+- unhandled promise issue while using while using `accountCopyIndex` ([#1154](https://github.com/algolia/algoliasearch-client-javascript/pull/1154))
 
 ## [v4.2.0](https://github.com/algolia/algoliasearch-client-javascript/compare/4.1.0...4.2.0)