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