Housekeeping - arc42 Docu

[MarkusTiede]

Topics

• 2 - solution strategy: either remove "open api" ref, or use it to document the REST interfaces
• 2 - solution strategy: add a compact description of the MVP system architecture (or refer to where it's documented
• 4. Cross-cutting Concepts: change wording in some places from "what can be done" to "what we've done", i.e. what are the actual concepts in the MVP. Change description of Hashing (it only relates to the OASI number)
• Security in general