Readme Update with pre-commit Pipeline

[AndreSlavescu]

Added complete pipeline to format files before contributing to repository.

automatically runs black on all files for formatting. automatically runs isort on all files for alphabetical ordering.

[ronakice]

I believe changes also need to be made to pyproject.toml?

[sahel-sh]

As we discussed in the chat, let's keep requirement changes separate. Ronak has already created an issue for it: https://github.com/castorini/rank_llm/issues/66

[ronakice]

@AndreSlavescu can we go about this as Sahel suggested? Sahel has a separate PR addressing this