Convert Level C from markdown to yaml
This merge request does not change any level C requirements.
The original LevelC.md file is now in yaml, following the format suggestion for the data pipe level C requirements.
Most important benefits:
- allow for schema validation of all entries
- allow to convert directly to excel without opening excel (!!). System engineering requests the level C in excel format, but this nice script from Karl allows as to bypass Excel.
For the review, I don't expect you do go through the files, it is text identical, just different format. Simply agree / not agree with this approach.