header_contents requires providing a header file extension in name argument

[wmmc88]

The below code fails because the name provided to the header_contents method doesn't have a valid c header file extension:

fn main() {
    bindgen::builder()
        .header_contents("input", "") // empty header
        .generate()
        .expect("Unable to generate bindings");
}

The docs don't mention this requirement and the error it creates doesn't actually say that this is the problem:

thread 'main' panicked at D:\.tools\.cargo\registry\src\index.crates.io-6f17d22bba15001f\bindgen-0.69.4\ir\context.rs:556:15:
  libclang error; possible causes include:
  - Invalid flag syntax
  - Unrecognized flags
  - Invalid flag arguments
  - File I/O errors
  - Host vs. target architecture mismatch
  If you encounter an error missing from this list, please file an issue or a PR!
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

I assumed that since the argument was name and since the docs didn't mention anything, that it would automatically append an appropriate file extension. I think the error should probably be updated and the docs too maybe.