Reuse Compatability

I changed a go project I have over to use spdx & the FSF's reuse tooling to attempt to make things more clear & simpler to manage. It looks like this license checker doesn't handle looking in a `LICENSES` directory for the SPDX licenses. The purpose for this issue is to see if that is something the maintainers here would be willing to accept a change for.

For reference, this is what reuse shows for it's structuring:
https://reuse.software/tutorial/#result

Here is my project (that uses the reuse cli tool):
https://github.com/schmidtw/goschtalt/tree/main/LICENSES

Of note is that the code isn't dual licensed (meaning it's available under both) but parts are covered by one license and other are covered by a different license.