".config" seems like such a natural name for it that I assumed it must be taken by some other program so they couldn't use it. I would expect a ".meta" folder to hold things like release history, a graph of the number of files in the project over time, links to external design documents, and other facts "about" the project. Not config files used by the project.
It kind of is... There is a formal standard that everyone ignores called XDG which defines the ".config" directory along with a few other handy common ones.
The XDG base directory specification defines a .config directory for user-specific configuration files (e.g. tmux.conf, i3's config file, a global gitignore file). This proposed standard would be for project-specific configuration files (e.g. a project-local .gitignore, .dir-locals.el, .mypy.ini).
