improve initial config

.gitignore

@@ -1,2 +1,5 @@
+# Comment if you want include Symfony project
 app
+
+# Ignore Database datas
 data

docker-compose.yml

@@ -4,8 +4,8 @@ services:
     db:
       image: postgres:12
       volumes:
-        # comment to keep data in docker volumes
-        - ./data:/var/lib/postgresql/data
+        # uncomment to keep data out of docker volumes
+        # - ./data:/var/lib/postgresql/data
         - ./docker_build/db/docker-entrypoint-initdb.d:/docker-entrypoint-initdb.d
       environment:
         - "POSTGRES_USER=postgres"