add changelog

Signed-off-by: Josh Romero <rmerqg@amazon.com>

CHANGELOG.md

@@ -20,6 +20,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Enable theme-switching via Advanced Settings to preview the Next theme ([#4475](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4475))
 - Optimize `augment-vis` saved obj searching by adding arg to saved obj client ([#4595](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4595))
 - Add resource ID filtering in fetch `augment-vis` obj queries ([#4608](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4608))
+- [Discover] Update styles to compatible with OUI `next` theme ([#4644](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4644))
 
 ### 🐛 Bug Fixes