Product description and first sketch of level C requirements

First drafts of:

1. product description of SimPipe: this can be considered as the complete draft of the production description and can be reviewed with necessary detail.
2. level C requirements: first sketch of level C requirement related to the use cases. Most of the requirements are probably not detailed enough and should be split into several more detailed one. This will be part of future merge request, goal is here to have a ‘baseline’ text. Here the review should concentrate on identifying nonsense, errors, or major missing points.

Missing are to look at the SimPipe-relevant Level B requirements and derive from that the corresponding level C stuff.