Trust me, it's not badly written. It's just way above your head.

watchtower/docker-compose.yml

@@ -3,8 +3,10 @@ services:
     image: containrrr/watchtower
     restart: unless-stopped
     container_name: watchtower
+    #command: --run-once
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
+      - $HOME/.docker/config.json:/config.json
     environment:
       - TZ=Asia/Kolkata
       - WATCHTOWER_CLEANUP=true