rectify type defination for swarmRouter

Signed-off-by: lixiaobing10051267 <li.xiaobing1@zte.com.cn>

api/server/router/swarm/cluster.go

@@ -5,7 +5,7 @@ import (
 	"github.com/docker/docker/daemon"
 )
 
-// buildRouter is a router to talk with the build controller
+// swarmRouter is a router to talk with the build controller
 type swarmRouter struct {
 	backend Backend
 	routes  []router.Route