add Ocata release notes

Change-Id: Iff0c7601f6ea1b35de1afb1d71b8aff08a967eab

releasenotes/notes/watcher-notifications-ovo-7b44d52ef6400dd0.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - Provide a notification mechanism into Watcher that supports versioning.
+    Whenever a Watcher object is created, updated or deleted, a versioned
+    notification will, if it's relevant, be automatically sent to notify in order
+    to allow an event-driven style of architecture within Watcher. Moreover, it
+    will also give other services and/or 3rd party softwares (e.g. monitoring
+    solutions or rules engines) the ability to react to such events.