Add Compliance and Audit Trail Documentation

[patdhlk]

Description

Document how X-as-Code supports compliance requirements (ISO 26262, ASPICE, etc.), highlighting where useblocks enterprise tooling adds value.

Acceptance Criteria

• Create docs/explanation/compliance.rst
• Cover:
  • Git history as audit trail
  • Traceability reports generation
  • Baseline/release management
  • Change impact analysis
• Standards to reference:
  • ISO 26262 (automotive)
  • ASPICE
  • DO-178C (aerospace)
  • IEC 62304 (medical)
• Enterprise section:
  • ubTrace for automated compliance reports
  • ubConnect for tool qualification evidence
  • Audit-ready exports