Update the Dockerfile to use the official caddy2 docker images

caddy/Dockerfile

@@ -1,5 +1,5 @@
-FROM abiosoft/caddy:no-stats
+FROM caddy/caddy:latest
 
-CMD ["--conf", "/etc/caddy/Caddyfile", "--log", "stdout", "--agree=true"]
+COPY ./caddy/Caddyfile /etc/caddy/Caddyfile
 
-EXPOSE 80 443 2015
+EXPOSE 80 443