Add documentation_url to the Package Class

[asimchoudhary]

Fixes #4092

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)

[asimchoudhary]

@pombredanne

I’ve raised a pull request addressing the issue “add documentation_url to the Package class”. The changes include:

• Initialization of the documentation_url field.
• Serialization and deserialization logic for the new field.
• Could you please review the PR when you get the chance? I’d appreciate your feedback on the
  implementation. Let me know if any additional changes are needed.

Thank you! 😊