Improve usage a bit.

--- class/mirror/geom_mirror.c	Tue Aug 10 21:52:12 2004
+++ sbin/geom/class/mirror/geom_mirror.c	Wed Aug 18 17:56:02 2004
@@ -25,7 +25,7 @@
  */
 
 #include <sys/cdefs.h>
-__FBSDID("$FreeBSD: src/sbin/geom/class/mirror/geom_mirror.c,v 1.3 2004/08/10 19:52:12 pjd Exp $");
+__FBSDID("$FreeBSD: src/sbin/geom/class/mirror/geom_mirror.c,v 1.4 2004/08/18 15:56:02 pjd Exp $");
 
 #include <sys/param.h>
 #include <errno.h>
@@ -117,7 +117,7 @@
 	    "       %s activate [-v] name prov [prov [...]]\n"
 	    "       %s deactivate [-v] name prov [prov [...]]\n"
 	    "       %s forget prov [prov [...]]\n"
-	    "       %s stop [-fv] name\n",
+	    "       %s stop [-fv] name [...]\n",
 	    comm, comm, comm, comm, comm, comm, comm, comm, comm, comm, comm);
 	exit(EXIT_FAILURE);
 }