This doesn’t enforce licensing/copyright headers to be present on all
files, but does check that at least a minimum number of files are
correct.
This should help avoid new files being added without appropriate
licensing information in future.
The baseline is set at what `reuse lint` outputs for me at the moment.
See https://reuse.software/tutorial/#step-2 for information about how to
add REUSE-compliant licensing/copyright to files.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #1415
