function showVolumeverlay(player, percentage) {
  const overlayJsx = (
    <div>
      <p>
        {percentage}
        {'%'}
      </p>
    </div>
  );

  showOneOffOverlay(player, OVERLAY_CLASS_SEEKED, overlayJsx, 'center');
}
Displays a transient "Volume Percentage" overlay.

@param player The videojs instance.
@param percentage how much % of volume active.