Add website building support for tutorials

[atharvas]

This adds a new folder which contains all the website related content. Need to run pip install jupyter-book ghp-import beforehand. A couple of high level TODOs:

• Enable github pages to allow publishing this website. For the actual library documentation, we should consider readthedocs.io. @mlb2251 any suggestions on what works best for this?
• Should we get a custom domain name for this website? Can we somehow use a subdomain of neurosymbolic.org? We also own neurosymbolic-learning.github.io.
• We need to write a small landing page with instructions for the tutorial notebooks and clean up the content of the tutorial notebooks themselves so they read properly on the website. Right now the landing page defaults to README.md which isn't really informative.