[Libvirt] Values overrides for external Ceph Cinder backend

Example values_overrides file is added to indicate how to
override the Libvirt manifest for configure an additional
externally managed Ceph Cinder backend.

Change-Id: I8e7a294059a2d98fb7854a281a29dcff80530d2b

libvirt/Chart.yaml

@@ -15,7 +15,7 @@ apiVersion: v1
 appVersion: v1.0.0
 description: OpenStack-Helm libvirt
 name: libvirt
-version: 0.1.2
+version: 0.1.3
 home: https://libvirt.org
 sources:
   - https://libvirt.org/git/?p=libvirt.git;a=summary

libvirt/values_overrides/cinder-external-ceph-backend.yaml

@@ -0,0 +1,16 @@
+# Note: This yaml file serves as an example for overriding the manifest
+# to enable additional externally managed Ceph Cinder backend. When additional
+# externally managed Ceph Cinder backend is provisioned as shown in
+# cinder/values_overrides/external-ceph-backend.yaml of repo openstack-helm,
+# below override is needed to store the secret key of the cinder user in
+# libvirt.
+---
+conf:
+  ceph:
+    cinder:
+      external_ceph:
+        enabled: true
+        user: cinder2
+        secret_uuid: 3f0133e4-8384-4743-9473-fecacc095c74
+        user_secret_name: cinder-volume-external-rbd-keyring
+...