Add jupyter notebook for Yu's tutorial: Understanding Plonk Protocol

[kurtpan666]

I think .ipynb files are not compatible with mdbook. I thought it might be helpful to investigate these sites first to learn about what is the best practice for adding ".ipynb" files:

• https://mybinder.readthedocs.io/en/latest/#
• https://colab.google/
• https://nbviewer.org/