Added missing CHANGELOG entry for PR 2613 (#2820)

Signed-off-by: Marco Pracucci <marco@pracucci.com>

CHANGELOG.md

@@ -25,6 +25,7 @@ We use *breaking* word for marking changes that are not backward compatible (rel
 - [#2658](https://github.com/thanos-io/thanos/pull/2658) [#2703](https://github.com/thanos-io/thanos/pull/2703) Upgrade to Prometheus [@3268eac2ddda](https://github.com/prometheus/prometheus/commit/3268eac2ddda) which is after v2.18.1.
     - TSDB now does memory-mapping of Head chunks and reduces memory usage.
 - [#2667](https://github.com/thanos-io/thanos/pull/2667) Store: removed support to the legacy `index.cache.json`. The hidden flag `--store.disable-index-header` was removed.
+- [#2613](https://github.com/thanos-io/thanos/pull/2613) Store: renamed the caching bucket config option `chunk_object_size_ttl` to `chunk_object_attrs_ttl`.
 - [#2667](https://github.com/thanos-io/thanos/pull/2667) Compact: the deprecated flag `--index.generate-missing-cache-file` and the metric `thanos_compact_generated_index_total` were removed.
 - [2603](https://github.com/thanos-io/thanos/pull/2603) Store/Querier: Significantly optimize cases where StoreAPIs or blocks returns exact overlapping chunks (e.g Store GW and sidecar or brute force Store Gateway HA).
 - [#2671](https://github.com/thanos-io/thanos/pull/2671) *breaking* Tools: bucket replicate flag `--resolution` is now in Go duration format.