It's not configuration though. Specifically, it's not configuration of the project in question, it's configuration for third party accessories.
If I'm writing an editor, I expect the config directory in the source code to hold the configuration for the editor, not .babelrc
meta is a much better name and they are "about" the project, not the project itself, so I disagree on that point. Though I agree it should not be hidden. I will start having a "meta" directory in my projects
But third party accessories are an essential part of any project these days, they aren't optional or afterthoughts. In that page they mention docker-compose.yml as once example. Most likely it's impossible (in its current state) to actually run that application without Docker.
Other things that would land in the folder:
- Files essential to building the project
- Files essential to running the test suite
- Files essential to developing on the project
IMO a "project" includes all those things. In your definition are those all "meta"? Does "meta" mean anything that's not source code?
On having it start with a dot: Why? Why would we pretend that these crucial files don't exist?
On having it named meta: These files aren't "about" the project or "above" the project, they ARE the project.