replaced fixed hostname in acme post hook with variable

docker-compose.yml

@@ -61,7 +61,7 @@ services:
                         proxy.${HOSTNAME},
                         push.${HOSTNAME}
       LETSENCRYPT_EMAIL: webmaster@${HOSTNAME}
-      ACME_POST_HOOK: "chmod a+r /etc/nginx/certs/im.s-up.net/key.pem"
+      ACME_POST_HOOK: chmod a+r /etc/nginx/certs/${HOSTNAME}/key.pem
 
     networks:
       - reverse-proxy_default