Advanced documentation / clean-up

[sdat2]

• Fix issue with documentation not compiling.
• Add a related work section to keep track of all of the different papers using a similar model.
• Delete as many files as possible.
• Add formulae to doc-strings.
• Add bibtex citations to docstrings.
• Add documentation page describing model in a simple way.
• Write a full-as-possible derivation of the model.
• Create youtube video to go through model.