Use local directory for mongo storage

It should prevent them from accidentally deleting.

docker-compose.yml

@@ -3,7 +3,9 @@ services:
    image: mongo:6.0.5
    restart: unless-stopped
    volumes:
-   - mongo-data:/data
+   - type: bind
+     source: ./mongo-data
+     target: /data/db
   wtb:
    image: wtb:latest
    restart: unless-stopped