Add AoUs, safety analysis, detailed design for vajson

### What

Add the following documentation pages for vajson: assumptions of use, safety analysis, detailed design.

### Acceptance Criteria (DoD)

- [ ] The documentation is added in the S-CORE format according to https://eclipse-score.github.io/process_description/main/folder_templates/modules/module_name/component_name/docs/index.html Alternatively, the documentation can be added in any other format (there will be follow up tasks to convert).

### How

_No response_