Update CHANGELOG.

Author: rhysrevans3

CHANGELOG.md

@@ -8,6 +8,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Changed
+
+- Simplified Patch class and updated patch script creation including adding nest creation for merge patch [#420](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/420)
 
 ## [v6.2.0] - 2025-08-27