Add independence in probability notebook

[Haleshot]

📝 Summary

Referred to the Independence chapter and created an initial draft of an interactive notebook.

• Appropriate LaTeX explaining relevant formulae involved in this topic.
• What I believe is a good interactive example to learn this concept.

Appropriate explanations for the above.

📋 Checklist

• I have included package dependencies in the notebook file using --sandbox
• If adding a course, include a README.md
• Keep language direct and simple.