add 'Caddy Server'

- signed-off-by: trimstray <trimstray@gmail.com>

README.md

@@ -579,6 +579,7 @@ performance of any of your sites from across the globe.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://varnish-cache.org/"><b>Varnish Cache</b></a> - HTTP accelerator designed for content-heavy dynamic web sites.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://nginx.org/"><b>Nginx</b></a> - open source web and reverse proxy server that is similar to Apache, but very light weight.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://github.com/alibaba/tengine"><b>Tengine</b></a> - a distribution of Nginx with some advanced features.<br>
+&nbsp;&nbsp;:small_orange_diamond: <a href="https://caddyserver.com/"><b>Caddy Server</b></a> - is an open source, HTTP/2-enabled web server with HTTPS by default.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://www.haproxy.org/"><b>HAProxy</b></a> - the reliable, high performance TCP/HTTP load balancer.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://traefik.io/"><b>Traefik</b></a> - open source reverse proxy/load balancer provides easier integration with Docker and Let's encrypt.<br>
 </p>