Adding license information.

[xvzcf]

I aimed to follow the KDE Licensing Guidelines, which follows the specifications of the reuse tool, which does license checking and linting.

[cjpatton]

Works for me, though I'm wondering if you tried to run the tool yourself? Seems like having this in our pockets would be useful, assuming it's not too hard to run ourselves.

[xvzcf]

I just had to run reuse lint, and here's the output:

# SUMMARY

* Bad licenses:
* Deprecated licenses:
* Licenses without file extension:
* Missing licenses:
* Unused licenses:
* Used licenses: Apache-2.0, BSD-3-Clause, CC0-1.0, MIT
* Read errors: 0
* Files with copyright information: 33 / 33
* Files with license information: 33 / 33

Congratulations! Your project is compliant with version 3.0 of the REUSE Specification :-)

And I agree, once I start working on the CI runner, I was planning on adding this to the CI for pull requests.