Follow MLA guidelines for capitalization of titles

[antoineco]

Originally posted by @cab105 in #29

According to MLA, all titles should follow some capitalization rules: https://style.mla.org/capitalization-of-titles/

An example of page using that style: https://style.mla.org/plagiarism-and-academic-dishonesty/

@cab105 mentioned we should stick to that style in doc pages, so we should update existing ones and remember to follow those rules in the future.