Update changelog

Author: whatnick

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 - CloudFerro logo to sponsors and supporters list [#485](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/485)
 - Latest news section to README [#485](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/485)
+- Added Helm chart for ES or OS in-cluster deployment [#455](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/455)
 
 ### Changed