Update file 12-cluster.md
Some more shuffling around of text to get a better and more natural flow. Also streamlining how MY_USER_NAME is mentioned in different places in the text.
Our GitLab instance (gitlab.sigma2.no) will be upgraded on Thursday (2025-12-18) around 16:00. A short downtime may be expected.
Some more shuffling around of text to get a better and more natural flow. Also streamlining how MY_USER_NAME is mentioned in different places in the text.