Update README.md for the deploy hooks.

deploy/README.md

@@ -93,8 +93,18 @@ If you are login as root, please specify the username to deploy cert to:
 export DEPLOY_CPANEL_USER=username
 acme.sh  --deploy  -d example.com  --deploy-hook cpanel_uapi
 ```
+## 8. Deploy the cert to your FRITZ!Box router
 
+You must specify the credentials that have administrative privileges on the FRITZ!Box in order to deploy the certificate, plus the URL of your FRITZ!Box, through the following environment variables:
+```sh
+$ export DEPLOY_FRITZBOX_USERNAME=my_username
+$ export DEPLOY_FRITZBOX_PASSWORD=the_password
+$ export DEPLOY_FRITZBOX_URL=https://fritzbox.example.com
+```
 
+After the first deployment, these values will be stored in your $HOME/.acme.sh/account.conf. You may now deploy the certificate like this:
 
-
+```sh
+acme.sh --deploy -d fritz.box --deploy-hook fritzbox
+```