Code optimisation and readability - Naive Bayes Classifier

[ruhi47]

Improvements:
Consistency and Readability:
Use consistent variable naming throughout the class (divided_classes, joint_prob, likelihood, etc.).

Efficiency:
Consider vectorization or optimization techniques for better performance, especially in loops iterating over data points.

Documentation:
Ensure all functions have clear docstrings describing parameters and return values for better readability and understanding.

[ruhi47]

I am GSSOC'24 Contributor. Please assign this issue to me. Thank you.