Feature request: include co-authors

[Guts]

As maintainer of a project where the co-authoring is encouraged, I'm missing the option supported by https://timvink.github.io/mkdocs-git-authors-plugin/options.html#add_co_authors.

With Material for Mkdocs and mkdocs-git-authors-plugin + https://github.com/ojacques/mkdocs-git-committers-plugin-2/:

With MaterialX and mkdocs-document-dates:

[jaywhj]

Alright, I will add support for this option in the next version.

[Guts]

Thanks you so much!