Fix dead link.

Author: wu-sheng

docs/en/setup/backend/backend-cluster.md

@@ -27,7 +27,7 @@ section `cluster`. You can specify any of them in the `selector` property to ena
 
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 **NOTICE**,
-Before you set up the cluster, please read the [Query Cluster Nodes](query_cluster_nodes.md) API to understand how to 
+Before you set up the cluster, please read the [Query Cluster Nodes](../../status/query_cluster_nodes.md) API to understand how to 
 verify the cluster node list. If the nodes don't match the expectation, the cluster is not working properly, there could 
 be many feature impacts, e.g. the metrics could be in accurate and the alarms could not be triggered correctly.
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