Added PR number to CHANGELOG

Signed-off-by: Marco Pracucci <[email protected]>

Author: pracucci

CHANGELOG.md

@@ -37,7 +37,7 @@
 * [CHANGE] Experimental TSDB: the querier in-memory index cache used by the experimental blocks storage shifted from per-tenant to per-querier. The `-experimental.tsdb.bucket-store.index-cache-size-bytes` now configures the per-querier index cache max size instead of a per-tenant cache and its default has been increased to 1GB. #2189
 * [CHANGE] If you are vendoring Cortex and use its components in your project, be aware that many Cortex components no longer start automatically when they are created. You may want to review PR and attached document. #2166
 * [CHANGE] Cortex now has /ready probe for all services, not just ingester and querier as before. In single-binary mode, /ready reports 204 only if all components are running properly. #2166
-* [CHANGE] Experimental TSDB: switched the blocks storage index header to the binary format. This change is expected to have no visible impact, except lower startup times and memory usage in the queriers. It's possible to switch back to the old JSON format via the flag `-experimental.tsdb.bucket-store.binary-index-header-enabled=false`.
+* [CHANGE] Experimental TSDB: switched the blocks storage index header to the binary format. This change is expected to have no visible impact, except lower startup times and memory usage in the queriers. It's possible to switch back to the old JSON format via the flag `-experimental.tsdb.bucket-store.binary-index-header-enabled=false`. #2223
 * [FEATURE] Added a read-only local alertmanager config store using files named corresponding to their tenant id. #2125
 * [FEATURE] Added user sub rings to distribute users to a subset of ingesters. #1947
   * `--experimental.distributor.user-subring-size`