ChangeLog entry for #2646 (#2663)

* add changelog entry

Signed-off-by: Jacob Lisi <[email protected]>

* Update CHANGELOG.md

Co-authored-by: gotjosh <[email protected]>
Signed-off-by: Jacob Lisi <[email protected]>

Co-authored-by: gotjosh <[email protected]>

Author: jtlisi

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## master / unreleased
 
+* [CHANGE] Experimental Ruler: Rule groups persisted to object storage using the experimental API have an updated object key encoding to better handle special characters. Rule groups previously-stored using object storage must be renamed to the new format. #2646
 * [CHANGE] Query Frontend now uses Round Robin to choose a tenant queue to service next. #2553
 * [CHANGE] `-promql.lookback-delta` is now deprecated and has been replaced by `-querier.lookback-delta` along with `lookback_delta` entry under `querier` in the config file. `-promql.lookback-delta` will be removed in v1.4.0. #2604
 * [CHANGE] Experimental TSDB: removed `-experimental.tsdb.bucket-store.binary-index-header-enabled` flag. Now the binary index-header is always enabled.
@@ -1138,4 +1139,4 @@ This release has several exciting features, the most notable of them being setti
   * `ha-tracker.cluster` is now `distributor.ha-tracker.cluster`
 * [FEATURE] You can specify "heap ballast" to reduce Go GC Churn #1489
 * [BUGFIX] HA Tracker no longer always makes a request to Consul/Etcd when a request is not from the active replica #1516
-* [BUGFIX] Queries are now correctly cancelled by the query-frontend #1508
+* [BUGFIX] Queries are now correctly cancelled by the query-frontend #1508