Update 'README.md'

README.md

@@ -1,3 +1,46 @@
 # certbot
 
-自动签发Let's Encrypt https免费证书
+自动签发Let's Encrypt https免费证书，python实现
+
+## Usage
+
+apt源安装
+```
+apt install snapd
+snap install --classic certbot
+ln -s /snap/bin/certbot /usr/bin/certbot
+```
+
+
+二级泛域名：
+```
+
+certbot certonly --manual \
+-d '*.b.exampple.com','example.com' \
+--agree-tos \
+--email domain@example.com \
+--server https://acme-v02.api.letsencrypt.org/directory
+```
+
+三级泛域名：
+```
+certbot certonly --manual \
+-d '*.b.exampple.com' \
+--agree-tos \
+--email domain@example.com \
+--server https://acme-v02.api.letsencrypt.org/directory
+```
+
+nginx 检出域名签名：
+
+```
+certbot certonly --nginx
+```
+
+自动更新证书
+
+```
+0 3 15 */1 * /usr/bin/certbot renew --dry-run
+```
+
+