https://blog.wongcw.com/2018/08/07/discuz%e6%b7%bb%e5%8a%a0nginx%e4%bc%aa%e9%9d%99%e6%80%81rewrite%e8%a7%84%e5%88%99%e7%9a%84%e6%96%b9%e6%b3%95/