Define Documentation Approach for Rust Code

We need to define a consistent approach for documenting Rust code across projects.

Relevant context:
🔗 [Implementation Concept – Units within the Component](https://eclipse-score.github.io/score/main/process/process_areas/implementation/implementation_concept.html#units-within-the-component)

A proposal has been made to evaluate [Sphinx-Rust](https://sphinx-rust.readthedocs.io/en/latest/) for integration into our Sphinx-based documentation toolchain.
Note: The project is currently in alpha, with the latest release dated April 2024.

Tasks:

- [ ] Evaluate Sphinx-Rust for stability and suitability

- [ ] Compare alternatives (e.g., rustdoc, mdBook)
- [ ] Define selection criteria (e.g., integration, maintainability, traceability)
- [ ] Document and communicate the chosen approach