Add note about current RC

Signed-off-by: Bryan Boreham <[email protected]>

Author: bboreham

CHANGELOG.md

@@ -11,6 +11,7 @@
 * [BUGFIX] Fix race in processing of headers in sharded queries. #2762
 
 ## 1.2.0 / 2020-06-xx
+(in progress of release: current release candidate is https://github.com/cortexproject/cortex/releases/tag/v1.2.0-rc.0)
 
 * [CHANGE] Metric `cortex_kv_request_duration_seconds` now includes `name` label to denote which client is being used as well as the `backend` label to denote the KV backend implementation in use. #2648
 * [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