Improvement: Add suggestions for the user how to integrate S-CORE

### What

There is a request to the process community to add suggestions for the user how to integrate S-CORE - discussed here: https://github.com/orgs/eclipse-score/discussions/407#discussioncomment-16973453. This should extend the AoU https://eclipse-score.github.io/score/main/requirements/platform_assumptions/index.html#aou_req__platform__testing and also take into account the outcome of https://github.com/eclipse-score/score/pull/2747.
Include also the expectation that all the module repositories he needs will be forked/mirrored by the user (as this will be needed for fast bug fixing and project specific adaptions (e.g. due to different target platform).

### Acceptance Criteria (DoD)

- [ ] found an appropriate place for the docu
- [ ] documented suggestion

### How

_No response_