natapp内网穿透，let’s encrypt 之 The error was: NoInstallationError()

错误信息：
The nginx plugin is not working; there may be problems with your existing configuration.
The error was: NoInstallationError()

Certbot默认使用nginx的路径，需求如下配置

ln -s /usr/local/nginx/sbin/nginx /usr/bin/nginx
ln -s /usr/local/nginx/conf/ /etc/nginx