update changelog

Signed-off-by: Josh Romero <[email protected]>

CHANGELOG.md

@@ -31,6 +31,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - [Vis Colors] Remove customized colors from sample visualizations and dashboards ([#4741](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4741))
 - [Decouple] Allow plugin manifest config to define semver compatible OpenSearch plugin and verify if it is installed on the cluster([#4612](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4612))
 - Adds Data explorer framework and implements Discover using it ([#4806](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4806))
+- [Theme] Make `next` theme the default ([#4854](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4854/))
 
 ### 🐛 Bug Fixes