[Site] Fixing docker config for mercure

Author: weaverryan

ux.symfony.com/docker-compose.yml

@@ -13,7 +13,7 @@ services:
       MERCURE_EXTRA_DIRECTIVES: |
         cors_origins https://127.0.0.1:9044
     # Comment the following line to disable the development mode
-    command: /usr/bin/caddy run -config /etc/caddy/Caddyfile.dev
+    command: /usr/bin/caddy run --config /etc/caddy/Caddyfile.dev
     volumes:
       - mercure_data:/data
       - mercure_config:/config