deviceset.go: fixed link in warning about udex sync is not supported

Signed-off-by: Laszlo Meszaros <lacienator@gmail.com>

daemon/graphdriver/devmapper/deviceset.go

@@ -1257,7 +1257,7 @@ func (devices *DeviceSet) initDevmapper(doInit bool) error {
 
 	// https://github.com/docker/docker/issues/4036
 	if supported := devicemapper.UdevSetSyncSupport(true); !supported {
-		logrus.Warn("Udev sync is not supported. This will lead to unexpected behavior, data loss and errors. For more information, see https://docs.docker.com/reference/commandline/cli/#daemon-storage-driver-option")
+		logrus.Warn("Udev sync is not supported. This will lead to unexpected behavior, data loss and errors. For more information, see https://docs.docker.com/reference/commandline/daemon/#daemon-storage-driver-option")
 	}
 
 	if err := os.MkdirAll(devices.metadataDir(), 0700); err != nil {