Need documentation enhancement to understand and use file-header

Hey,

I stumbled across the file-header crate while looking for a way to manage file headers in my project, but I’m struggling to figure out what this library does or how to use it. The README is super short and only mentions that it’s a Rust library for “checking and adding headers to files” with some SPDX license support. But that’s it! There’s no explanation of what “headers” mean in this context, how to set it up, or what kind of use cases it’s meant for.

I can try to draft some of this myself, but I’d need a bit of guidance from the maintainers on what’s expected. Thanks for maintaining this project! I think it has potential, but it’s hard to get started without more info.