cenos7 virubual box Add storage

 https://sam.liho.tw/2020/07/06/virtualbox-%E6%94%B9%E8%AE%8A-centos-7-%E7%A1%AC%E7%A2%9F%E5%A4%A7%E5%B0%8F-%E8%AE%8A%E5%A4%A7%E7%82%BA%E4%BE%8B/