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