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 will have an OS upgrade on 2024-12-30 at 12:00. A couple of hours of downtime must be expected. Happy holidays, everyone
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.