[Docker] top-level network “webnet” is ignored 오류, service “web”: network “webnet” is ignored 오류

도커 튜토리얼에 따라 아래 명령어 실행시 오류 발생.. $ docker stack deploy -c docker-compose.yml getstartedlab top-level network “webnet” is ignored,  service “web”: network “webnet” is ignored  왜인지 모르겠으나, 가운데 옵션...