[Kibana] remove useless maxUnavailable in Kibana chart (#422)

kibana/README.md

@@ -72,7 +72,6 @@ helm install --name kibana elastic/kibana --set imageTag=7.5.1
 | `serviceAccount`          | Allows you to overwrite the "default" [serviceAccount](https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/) for the pod                                                                                                                                                                                                        | `[]`                                                                                                                      |
 | `priorityClassName`       | The [name of the PriorityClass](https://kubernetes.io/docs/concepts/configuration/pod-priority-preemption/#priorityclass). No default is supplied as the PriorityClass must be created first.                                                                                                                                                                  | `""`                                                                                                                      |
 | `httpPort`                | The http port that Kubernetes will use for the healthchecks and the service.                                                                                                                                                                                                                                                                                   | `5601`                                                                                                                    |
-| `maxUnavailable`          | The [maxUnavailable](https://kubernetes.io/docs/tasks/run-application/configure-pdb/#specifying-a-poddisruptionbudget) value for the pod disruption budget. By default this will prevent Kubernetes from having more than 1 unhealthy pod                                                                                                                      | `1`                                                                                                                       |
 | `updateStrategy`          | Allows you to change the default update [strategy](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#updating-a-deployment) for the deployment. A [standard upgrade](https://www.elastic.co/guide/en/kibana/current/upgrade-standard.html) of Kibana requires a full stop and start which is why the default strategy is set to `Recreate` | `Recreate`                                                                                                                |
 | `readinessProbe`          | Configuration for the [readinessProbe](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-probes/)                                                                                                                                                                                                                          | `failureThreshold: 3`<br>`initialDelaySeconds: 10`<br>`periodSeconds: 10`<br>`successThreshold: 3`<br>`timeoutSeconds: 5` |
 | `imagePullSecrets`        | Configuration for [imagePullSecrets](https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/#create-a-pod-that-uses-your-secret) so that you can use a private registry for your image                                                                                                                                           | `[]`                                                                                                                      |

kibana/values.yaml

@@ -73,11 +73,6 @@ priorityClassName: ""
 
 httpPort: 5601
 
-# This is the max unavailable setting for the pod disruption budget
-# The default value of 1 will make sure that kubernetes won't allow more than 1
-# of your pods to be unavailable during maintenance
-maxUnavailable: 1
-
 updateStrategy:
   type: "Recreate"