Update the project README

[pawkedzia]

Refresh the repository’s README.md to include:

• An overview of the data mapping process (source fields → target fields).
• A clear explanation of the PII anonymization approach, covering:
  • Which personal identifiers are detected.
  • The hashing/salting technique used.
• Example usage snippets showing how to run the anonymizer.
• Links to relevant configuration files or documentation sections.