use <> in the usage

Signed-off-by: Victor Vieux <vieux@docker.com>

flags.go

@@ -31,12 +31,6 @@ var (
 		Value: homepath(".swarm"),
 		Usage: "",
 	}
-	flDiscovery = cli.StringFlag{
-		Name:   "discovery",
-		Value:  "",
-		Usage:  "discovery service to use [token://<token>,\n\t\t\t\t  etcd://<ip1>,<ip2>/<path>,\n\t\t\t\t  file://path/to/file,\n\t\t\t\t  consul://<addr>/<path>,\n\t\t\t\t  zk://<ip1>,<ip2>/<path>,\n\t\t\t\t  <ip1>,<ip2>]",
-		EnvVar: "SWARM_DISCOVERY",
-	}
 	flAddr = cli.StringFlag{
 		Name:   "addr",
 		Value:  "127.0.0.1:4243",

help.go

@@ -7,7 +7,7 @@ func init() {
 	cli.CommandHelpTemplate = `{{$DISCOVERY := or (eq .Name "manage") (eq .Name "join") (eq .Name "list")}}NAME:
    {{.Name}} - {{.Usage}}
 USAGE:
-   swarm {{.Name}}{{if .Flags}} [command options]{{end}} {{if $DISCOVERY}}[discovery]{{end}}{{if .Description}}
+   swarm {{.Name}}{{if .Flags}} [options]{{end}} {{if $DISCOVERY}}<discovery>{{end}}{{if .Description}}
 DESCRIPTION:
    {{.Description}}{{end}}{{if $DISCOVERY}}
 ARGUMENTS: