Update healthcheck related examples and add head support (#5650)

- Add head method for healthcheck endpoint. Some platforms/users
may use the HTTP Head method to check for health status.

- Add liveness and readiness probe examples in Kubernetes yaml
example docs. Note that readiness probe not added to StatefulSet
example due to https://github.com/kubernetes/kubernetes/issues/27114

docs/orchestration/kubernetes-yaml/minio-distributed-statefulset.yaml

@@ -35,6 +35,15 @@ spec:
         volumeMounts:
         - name: data
           mountPath: /data
+        # Liveness probe detects situations where Minio server instance
+        # is not working properly and needs restart. Kubernetes automatically
+        # restarts the pods if liveness checks fail.
+        livenessProbe:
+          httpGet:
+            path: /minio/health/live
+            port: 9000
+          initialDelaySeconds: 120
+          periodSeconds: 20
   # These are converted to volume claims by the controller
   # and mounted at the paths mentioned above.
   volumeClaimTemplates: