Motivation
If we can detect the license (see #78 for a way to do this with the identify package), then we can create a badge for it.

If we can't identify the license from the file (and we might have to check different filenames?) then perhaps we can identify it from pyproject.toml (or setup.cfg? or setup.py? From the built package?) through either the project.license field or maybe the classifiers.

If there is a License file, but we can't identify it, perhaps we put the license as "Other" or "Unknown", and warn the user.

If there's no license file, and no other trace of a license, we could probably suppose the code is proprietary, in which case we should avoid the term "License" - since there is no license. Obviously we'd warn in this case too.

Summary of desired enhancement
Create a badge giving the license.