scanner: use descriptions in entries

[James Legg]

This series fixes https://gitlab.freedesktop.org/wayland/wayland/-/issues/208
and alters a test to confirm it.

I know I'm supposed to use a gitlab pull request, but I can't create an
account as there is an error with reCAPTCHA, already reported here:
https://lists.freedesktop.org/archives/sitewranglers/2021-May/013103.html
and I wouldn't use proprietary javascript to provide training data for a
proprietary machine learning system even if reCAPTCHA did load.

James