Updated gitignore

I don't know exactly why, but I can't get gitignore to remove these
LaTeX files. It's not a big problem tho, so I'll just remove these three
lines.
[report]: Less footnotes and unnecessary citations

I removed some footnotes that weren't really helpful, an example of
markov chains that wasn't necessary (whoever reads this should have a
reasonable mathematical background) and some references that didn't add
much.

I need to reorganize this document goddamnit.