Add Caddy web server configuration in the docs

[hj-collab]

Hi,

You might be aware of Caddy Web Server. It's fast and easy to use web server which handles SSL certs automatically.

I have noticed that there is Apache & Nginx conf available in the plugin docs. https://www.keycdn.com/support/wordpress-cache-enabler-plugin#advanced-configuration

Here is a caddy config file supporting cache enabler which I also use on daily basis. First in this post. https://caddy.community/t/example-configure-wordpress-with-a-static-cache/8215

Please also make it available in your docs. So newer users don't need to roam around to find the right config. :)