Update CHANGELOG.md

Author: cgillum

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add API to set custom status ([#81](https://github.com/microsoft/durabletask-go/pull/81)) - by [@famarting](https://github.com/famarting)
 - Add missing purge orchestration options ([#82](https://github.com/microsoft/durabletask-go/pull/82)) - by [@famarting](https://github.com/famarting)
+- Add support for retry policies ([#83](https://github.com/microsoft/durabletask-go/pull/83)) - by [@famarting](https://github.com/famarting)
 
 ### Changed