https://letsencrypt.org/
https://letsencrypt.org/docs/client-options/
选择ACMESharp
powershell 下的具体操作方式参考：
1.https://github.com/ebekker/ACMESharp/wiki/Quick-Start
2.https://pkisharp.github.io/ACMESharp-docs/Quick-Start
免费SSL申请
原文：https://www.cnblogs.com/zzfstudy/p/9357358.html
