Contribution to the project for Python Gradient Descent

[dfzunigah]

Hello! Hope you're doing great!

A huge thank you for developing these Numerical Tours, it has been a blessing as a guidance for my Intro to AI course.

I want to contribute to the project, specifically in the Python Gradient Descent Notebook. I coded the solutions for exercises 4 and 5 (adapted from the ones you did in MATLAB), improved the code for solution 3 and fixed some typos in the notebook.

It would be cool to know if it would be in your interest to update the repository or give me some feedback on them.

@gpeyre @pierrestock @blink1073

Greetings from Colombia, take care,