F-Droid doesn't fall back to the `main` changelog, so at the moment
the Bangle.js Gadgetbridge flavor shows in the store without one.
For now at least, the easiest way to add changelogs seems to be to
simply symlink to the `main` flavor.
See https://codeberg.org/Freeyourgadget/Gadgetbridge/pulls/2776 for
discussion about file duplication vs. symlinking vs. separate changelogs.