clang topics: Add more guiding (by me) to and re-prioritize exercise

[langchr86]

Multiple feedbacks mentioned that docker is more interesting then ansible. This cannot be easily solved. But an addition feedback is that the corresponding exercises are too much automized and therefore not that useful. Maybe I should create my own exercise (based on the existing ones) which are more guided by me. This also increase interactivity in the group.

CMake part/exercise could be shrinked down.