updating docs

x-pack/filebeat/filebeat.reference.yml

@@ -3152,6 +3152,7 @@ filebeat.inputs:
 # - type: kubernetes
 # node: ${NODE_NAME}
 # hints.enabled: true
+# # By default requests to kubeadm config map are made in order to enrich cluster name by requesting /api/v1/namespaces/kube-system/configmaps/kubeadm-config API endpoint.
 # use_kubeadm: true
 # hints.default_config:
 # type: filestream