Updated CHANGELOG.md

Signed-off-by: mzardab <mzardab@redhat.com>

CHANGELOG.md

@@ -20,6 +20,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 - [#4946](https://github.com/thanos-io/thanos/pull/4946) Store: Support tls_config configuration for the s3 minio client.
 - [#4974](https://github.com/thanos-io/thanos/pull/4974) Store: Support tls_config configuration for connecting with Azure storage.
 - [#4999](https://github.com/thanos-io/thanos/pull/4999) COS: Support `endpoint` configuration for vpc internal endpoint.
+- [#5059](https://github.com/thanos-io/thanos/pull/5059) Compactor: Adding minimum retention flag validation for downsampling retention.
 
 ### Fixed
 - [#4918](https://github.com/thanos-io/thanos/pull/4918) Tracing: Fixing force tracing with Jaeger.