Feat: added notebook to the scikit-learn example

[flaviassantos]

This PR is in response to #247.

Changes

A Jupyter notebook Hamilton for ML dataflows.ipynb was added to the repo.

How I tested this

I ran all cells successfully and ran pre-commit check.

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.

[skrawcz]

🚢 🇮🇹 ! ❤️