Update pod-disruption-budget.md

add missing PDB for master nodes

Author: mjmbischoff

deploy-manage/deploy/cloud-on-k8s/pod-disruption-budget.md

@@ -102,6 +102,17 @@ spec:
         node.roles: ["data_hot", "data_content", "ingest"]
         node.store.allow_mmap: false
 
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: master-nodes-pdb
+spec:
+  minAvailable: 2 <2>
+  selector:
+    matchLabels:
+      elasticsearch.k8s.elastic.co/cluster-name: quickstart <3>
+      elasticsearch.k8s.elastic.co/statefulset-name: quickstart-es-master <4>
+
 apiVersion: policy/v1
 kind: PodDisruptionBudget
 metadata: