Make show-config work with cluster_name from config file
similar to edit-config, list and so on
@@ -1101,7 +1101,7 @@ def edit_config(obj, cluster_name, force, quiet, kvpairs, pgkvpairs, apply_filen
@ctl.command('show-config', help="Show cluster configuration")
-@click.argument('cluster_name')
+@arg_cluster_name
@click.pass_obj
def show_config(obj, cluster_name):
cluster = get_dcs(obj, cluster_name).get_cluster()
