官方文档：https://nginx.org/en/linux_packages.html#RHEL-CentOS
安装环境：Linux 服务器 CentOS 7.3、Root 权限
1、Install the prerequisites:
sudo yum install yum-utils
2、To set up the yum repository, create the file named /etc/yum.repos.d/nginx.repo with the following c
