Add releasenote to tag the Patrole for Xena release

This commit adds the releasenote to tag Patrole for Xena
release.

Change-Id: I9f1adc63e59581de90fea6426be665c71a9158c0
diff --git a/releasenotes/notes/patrole-xena-release-66df296a5d4f5e8e.yaml b/releasenotes/notes/patrole-xena-release-66df296a5d4f5e8e.yaml
new file mode 100644
index 0000000..83c598a
--- /dev/null
+++ b/releasenotes/notes/patrole-xena-release-66df296a5d4f5e8e.yaml
@@ -0,0 +1,17 @@
+---
+prelude: |
+    This release is to tag the Patrole for OpenStack Xena release.
+    This release marks the start of Xena release support in Patrole.
+    After this release, Patrole will support below OpenStack Releases:
+
+    * Xena
+    * Wallaby
+    * Victoria
+    * Ussuri
+
+    Current development of Patrole is for OpenStack Yoga development
+    cycle. Every Patrole commit is also tested against master during
+    the Yoga cycle. However, this does not necessarily mean that using
+    Patrole as of this tag will work against a Xena (or future release)
+    cloud.
+    To be on safe side, use this tag to test the OpenStack Xena release.