Documentation: Cluster naming conventions.

Fixes #5806

doc/6.04-cluster.md

@@ -129,7 +129,50 @@ In order to load configuration files which were received from a remote Icinga 2
 instance you will have to add the following include directive to your
 `icinga2.conf` configuration file:
 
-    include IcingaLocalStateDir + "/lib/icinga2/cluster/config/*/*"
+    include_recursive IcingaLocalStateDir + "/lib/icinga2/cluster/config"
+
+### <a id="cluster-naming-convention"></a> Cluster Naming Convention
+
+The SSL certificate common name (CN) will be used by the [ClusterListener](pbjecttype-clusterlistener)
+object to determine the local authority. This name must match the local [Endpoint](#objecttype-endpoint)
+object name.
+
+Example:
+
+    # icinga2-build-key icinga-node-1
+    ...
+    Common Name (e.g. server FQDN or YOUR name) [icinga-node-1]:
+
+    # vim cluster.conf
+
+    object Endpoint "icinga-node-1" {
+      host = "icinga-node-1.localdomain",
+      port = 8888
+    }
+
+The [Endpoint](#objecttype-endpoint) name is further referenced as `peers` attribute on the
+[ClusterListener](pbjecttype-clusterlistener) object.
+
+    object Endpoint "icinga-node-2" {
+      host = "icinga-node-2.localdomain",
+      port = 8888
+    }
+
+    object ClusterListener "cluster" {
+      ca_path = "/etc/icinga2/ca/ca.crt",
+      cert_path = "/etc/icinga2/ca/icinga-node-1.crt",
+      key_path = "/etc/icinga2/ca/icinga-node-1.key",
+
+      bind_port = 8888,
+
+      peers = [ "icinga-node-2" ]
+    }
+
+Specifying the local node name using the [IcingaNodeName](#global-constants) variable requires
+the same name as used for the endpoint name and common name above. If not set, the FQDN is used.
+
+    const IcingaNodeName = "icinga-node-1"
+
 
 ### <a id="initial-cluster-sync"></a> Initial Cluster Sync