fix: ws proxy port config

etc/emqx.conf

@@ -1618,7 +1618,7 @@ listener.ws.external.access.1 = allow all
 ## deployed behind NGINX or HAProxy.
 ##
 ## Default: X-Forwarded-Port
-## listener.ws.external.proxy_address_header = X-Forwarded-Port
+## listener.ws.external.proxy_port_header = X-Forwarded-Port
 
 ## Enable the Proxy Protocol V1/2 if the EMQ cluster is deployed behind
 ## HAProxy or Nginx.