add comment for use case

content/docs/2.14/operate/cluster.md

@@ -136,7 +136,7 @@ The Metrics Service config used by the KEDA Metrics Adapter to connect to the KE
 |     Adapter Flag                    | Default Value                                     | Description                                    |
 | ----------------------------------- | ------------------------------------------------- | ---------------------------------------------- |
 | metrics-service-address             | keda-operator.keda.svc.cluster.local:9666         | The address of the GRPC Metrics Service Server |
-| metrics-service-grpc-authority      | ""                                                | Host Authority override for the Metrics Service if the Host Authority is not the same as the address used for the GRPC Metrics Service Server. |
+| metrics-service-grpc-authority      | ""                                                | Host Authority override for the Metrics Service if the Host Authority is not the same as the address used for the GRPC Metrics Service Server. This is required for mutual TLS when the identity of the adapter server as presented in its TLS certificate is not the same as the metrics-service-address |
 
 ## Configure `MaxConcurrentReconciles` for Controllers