1.2.3 release notes (#89)

* 1.2.3 release notes

* Adding released date

Author: jeff-allen-mongo

source/release-notes.txt

@@ -12,6 +12,25 @@ Release Notes for |k8s-op-full|
    :depth: 1
    :class: singlecol
 
+.. _ent-op-1.2.3:
+
+|k8s-op-full| 1.2.3
+-------------------
+
+*Released 2019-09-13*
+
+- **Update:** The |k8s-op-full| will remove support for multiple
+  clusters per project in a future release. If a project contains more
+  than one cluster, a warning will be added to the status of the
+  MongoDB Resources. Additionally, any new cluster being added to a
+  non-empty project will result in a :guilabel:`Failed` state, and won't
+  be processed.
+
+- **Fix:** The overall stability of the operator has been improved. The
+  operator is now more conservative in resource updates both on
+  |k8s| and |com|.
+
+
 .. _ent-op-1.2.2:
 
 |k8s-op-full| 1.2.2