矿渣联想云 Armbian 更换国内源

玩联想云，装的Armbian系统，旧源不能用，换！

文件路径：/etc/apt/sources.list

deb http://mirrors.ustc.edu.cn/debian stretch main contrib non-free
deb http://mirrors.ustc.edu.cn/debian stretch-updates main contrib non-free
deb http://mirrors.ustc.edu.cn/debian stretch-backports main contrib non-free
deb http://mirrors.ustc.edu.cn/debian-security/ stretch/updates main contrib non-free

原文地址：https://www.jianshu.com/p/beee8054c560