Make sure `update.sh` knows log file
See currently rendered README which states:
- Download logs are in [log/update.log](log/update.log).A replacement for the old instance build runner (old tags dind/docker-in-docker) is available. For details see https://git.geomar.de/open-source/gitlab-docu/-/wikis/build_runner
See currently rendered README which states:
- Download logs are in [log/update.log](log/update.log).