update README, examples and RBAC to include leader election

deploy/kubernetes/rbac.yaml

@@ -63,3 +63,30 @@ roleRef:
   # change the name also here if the ClusterRole gets renamed
   name: external-snapshotter-runner
   apiGroup: rbac.authorization.k8s.io
+
+---
+kind: Role
+apiVersion: rbac.authorization.k8s.io/v1
+metadata:
+  namespace: default # TODO: replace with the namespace you want for your sidecar
+  name: external-snapshotter-leaderelection
+rules:
+- apiGroups: ["coordination.k8s.io"]
+  resources: ["leases"]
+  verbs: ["get", "watch", "list", "delete", "update", "create"]
+
+---
+kind: RoleBinding
+apiVersion: rbac.authorization.k8s.io/v1
+metadata:
+  name: external-snapshotter-leaderelection
+  namespace: default # TODO: replace with the namespace you want for your sidecar
+subjects:
+  - kind: ServiceAccount
+    name: csi-snapshotter
+    namespace: default # TODO: replace with the namespace you want for your sidecar
+roleRef:
+  kind: Role
+  name: external-snapshotter-leaderelection
+  apiGroup: rbac.authorization.k8s.io
+