ssl cer doc

ssl证书生成.md

+1. 下载certbot-auto
+1. 下载certbot-auto
+```
+wget https://dl.eff.org/certbot-auto
+```
+2. 添加可执行权限
+```
+chmod +x certbot-auto
+```
+3. 安装nginx
+```
+yum install nginx -y
+```
+4. 手动更新证书的txt记录, 并在dns里面修改txt记录
+```
+./certbot-auto certonly -d *.xxxx.com -i --manual
+```
+5. 配置用nginx自动更新,即可完成
+```
+./certbot-auto certonly -d *.xxx.com -i nginx
+```