add release note

Signed-off-by: Sean Teeling <[email protected]>

Author: steeling

docs/release_notes.md

@@ -1,5 +1,19 @@
 # Release Notes
 
+## Release v1.2.0
+
+### Notable changes
+
+- Root certificate rotation is now supported through the new CRD, MeshRootCertificate.
+- Along with root certificate rotation we support custom trust domains, as well as rotating to new trust domains with no downtime.
+
+### Breaking Changes
+
+- The following metrics no longer use the label `common_name`, due to the fact that the common name's trust domain can rotate. Instead 2 new labels, `proxy_uuid` and `identity` have been added.
+  - `osm_proxy_response_send_success_count`
+  - `osm_proxy_response_send_error_count`
+  - `osm_proxy_xds_request_count`
+		
 ## Release v1.1.0
 
 ### Notable changes