Start 1.11 release; add changelog entries for #4505 (#4507)

* Add 1.11.0-rc.0 marker to CHANGELOG
* Add changelog entries for #4505

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

Author: bboreham

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## master / unreleased
 
+
+## 1.11.0-rc.0 in progress
+
 * [CHANGE] Memberlist: Expose default configuration values to the command line options. Note that setting these explicitly to zero will no longer cause the default to be used. If the default is desired, then do set the option. The following are affected: #4276
   - `-memberlist.stream-timeout`
   - `-memberlist.retransmit-factor`
@@ -18,6 +21,7 @@
 * [FEATURE] Query Frontend: Add `cortex_query_fetched_series_total` and `cortex_query_fetched_chunks_bytes_total` per-user counters to expose the number of series and bytes fetched as part of queries. These metrics can be enabled with the `-frontend.query-stats-enabled` flag (or its respective YAML config option `query_stats_enabled`). #4343
 * [FEATURE] AlertManager: Add support for SNS Receiver. #4382
 * [FEATURE] Distributor: Add label `status` to metric `cortex_distributor_ingester_append_failures_total` #4442
+* [FEATURE] Queries: Added `present_over_time` PromQL function, also some TSDB optimisations. #4505
 * [ENHANCEMENT] Add timeout for waiting on compactor to become ACTIVE in the ring. #4262
 * [ENHANCEMENT] Reduce memory used by streaming queries, particularly in ruler. #4341
 * [ENHANCEMENT] Ring: allow experimental configuration of disabling of heartbeat timeouts by setting the relevant configuration value to zero. Applies to the following: #4342