Update the Original Research page of the wiki
Update the Original Research page of the wiki

- Add a small section about quick_merge_sort
- Fix the section about the best-known comparison sort complexities
- Include vergesort actual complexity and improved complexity for
bidirectional iterators
- Mention that vergesort can be made stable if needed

[ci skip]

Morwenn/cpp-sort,Morwenn/cpp-sort,Morwenn/cpp-sort,Morwenn/cpp-sort