docs: Expand CycloneDX parser documentation with detailed field mappings

Added detailed documentation for CycloneDX parser including:
  - Field mapping tables for both JSON and XML formats
  - Special processing notes for dates, severity, status conversion
  - CVSS processing details and component lookup mechanics
  - Deduplication and vulnerability ID collection explanations
  - Legacy format support and namespace handling (XML)

  Authored by T. Walker - DefectDojo

Author: skywalke34