Improve REUSE recommendations

[andreashaerter]

Our current approach to introduce REUSE is

1. .reuse/dep5 with Files: * stanza
2. Use header comment in files with a high profitability to be used stand-alone, e.g. script files
3. The header must state the same license as the default or an explicit entry in .reuse/dep5

The main reasoning for this was (after discussions):

1. Having a compliant default is a good machine readable staring point and far better than simple LICENSE files + README.md entry, especially as preparation for multiple licenses
2. the reuse lint tool complains with a deprecation warning even if the license in .reuse/dep5 and the inline header is exactly the same.

We like the default as it prevents the need to put license information for very few, insignificant files and tooling directories while still making it technically easy to determine the license plus putting license headers in nearly every file in the future.

However, our .reuse/dep5 with Files: * stanza-default seems to be strongly discouraged (see fsfe/reuse-docs#117, especially one comment). We therefore should discuss how to proceed and how to adapt licensing-how-to-apply.md.

Additionally, the Gem used by GitHub and others is still not able to detect the license of our repositories automatically because of this. Symlinks might be the solution (but this is a good example why Files: * is so pleasant... it is clumsy to have a LICENSE file because of licensee-Gem issues even if a LICENSE.license is not needed as REUSE ignores a COPYING or LICENSE file in the root).

Licensee even does not support symlinks (while reuse lint does), so one could only put a LICENSE file in the project root and create a Symlink to it in the LICENSES directory to prevent duplication.

[andreashaerter]

One quick idea: What happens if the dep5 file is referencing non-existing files? We could

1. implement a dep5 starter template containing information for all insignificant files to-be-expected, comparable to a good .gitignore
2. get rid of Files: * and put a license header into practically all files like it is the intention of REUSE

if specifying non-existent files triggers no problems.

[andreashaerter]

It is in fact no problem to define stanzas for non-existing files in the dep5 file. Providing a sane template is probably a good way to solve the issue.

[andreashaerter]

Closing this now ater new discussions and improvements. Summary

• The stanza using a wildcard as default makes sense, the deprecation warning seems to be a bug (cf. issue 885)
• We changed our current recommendation and will add license comment headers in most files (cf. fab6bf8)

We will open a new issue if the current recommendation turns out to be impractical.