feat: allow to install the website skeleton (#152)

* feat: allow to install the website skeleton

* wip

* wip

* cleanup

* revert rename in docs

* cleanup

docker-compose.yml

@@ -7,6 +7,7 @@ services:
       target: symfony_php
       args:
         SYMFONY_VERSION: ${SYMFONY_VERSION:-}
+        SKELETON: ${SKELETON:-symfony/skeleton}
         STABILITY: ${STABILITY:-stable}
     restart: unless-stopped
     volumes:
@@ -23,7 +24,6 @@ services:
       MERCURE_URL: ${CADDY_MERCURE_URL:-http://caddy/.well-known/mercure}
       MERCURE_PUBLIC_URL: https://${SERVER_NAME:-localhost}/.well-known/mercure
       MERCURE_JWT_SECRET: ${CADDY_MERCURE_JWT_SECRET:-!ChangeMe!}
-      SYMFONY_VERSION:
 
   caddy:
     build: