update changelog

Signed-off-by: Jakob Kartschall <[email protected]>

Author: Jakob Kartschall

CHANGELOG.md

@@ -87,6 +87,7 @@
 * [ENHANCEMENT] Flusher: Added `-flusher.exit-after-flush` option (defaults to true) to control whether Cortex should stop completely after Flusher has finished its work. #2877
 * [ENHANCEMENT] Added metrics `cortex_config_hash` and `cortex_runtime_config_hash` to expose hash of the currently active config file. #2874
 * [ENHANCEMENT] Logger: added JSON logging support, configured via the `-log.format=json` CLI flag or its respective YAML config option. #2386
+* [ENHANCEMENT] Clarify limitations to the `/api/v1/series` endpoint. #2953
 * [BUGFIX] Fixed a bug in the index intersect code causing storage to return more chunks/series than required. #2796
 * [BUGFIX] Fixed the number of reported keys in the background cache queue. #2764
 * [BUGFIX] Fix race in processing of headers in sharded queries. #2762