Add CHANGELOG.md entry.

Signed-off-by: Peter Štibraný <[email protected]>

Author: pstibrany

CHANGELOG.md

@@ -28,6 +28,7 @@
 * [ENHANCEMENT] Query-frontend: Small optimization on top of PR #3968 to avoid unnecessary Extents merging. #4026
 * [ENHANCEMENT] Add a metric `cortex_compactor_compaction_interval_seconds` for the compaction interval config value. #4040
 * [ENHANCEMENT] Ingester: added following per-ingester (instance) limits: max number of series in memory (`-ingester.instance-limits.max-series`), max number of users in memory (`-ingester.instance-limits.max-tenants`), max ingestion rate (`-ingester.instance-limits.max-ingestion-rate`), and max inflight requests (`-ingester.instance-limits.max-inflight-push-requests`). These limits are only used when using blocks storage. Limits can also be configured using runtime-config feature, and current values are exported as `cortex_ingester_instance_limits` metric. #3992.
+* [ENHANCEMENT] Cortex is now built with Go 1.16. #4062
 * [BUGFIX] Ruler-API: fix bug where `/api/v1/rules/<namespace>/<group_name>` endpoint return `400` instead of `404`. #4013
 * [BUGFIX] Distributor: reverted changes done to rate limiting in #3825. #3948
 * [BUGFIX] Ingester: Fix race condition when opening and closing tsdb concurrently. #3959