Add a section for service load balancer cleanup

content/en/docs/tasks/access-application-cluster/create-external-load-balancer.md

@@ -194,6 +194,24 @@ Known issues:
 
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+## Load Balancer cleanup
+
+In usual case, the correlating load balancer resources in cloud provider should
+be cleaned up soon after a LoadBalancer type service is deleted. But it is known
+that there are various corner cases where resources can be leaved orphaned after
+a service is deleted. Finalizer Protection for Service LoadBalancers was
+introduced to prevent this from happening. By using finalizer, this feature
+makes sure service resource is not fully deleted until the correlating load
+balancer resources are deleted.
+
+Specifically, a finalizer with name `"service.kubernetes.io/load-balancer-cleanup"`
+will be attached to the service if any load balancer resource is created for it.
+The finalizer will only be removed after load balancer resource is cleaned up.
+Above ensures resource won't be leaked even in corner cases.
+
+This feature was introduced as Alpha in kubernetes v1.15. It can be enabled via
+feature gate `ServiceLoadBalancerFinalizer=true`.
+
 ## External Load Balancer Providers
 
 It is important to note that the datapath for this functionality is provided by a load balancer external to the Kubernetes cluster.