Improve F-Droid listing

[mueller-ma]

I've seen this app on F-Droid, but it lacks screenshots, changelog and a translatable description there. It's pretty easy for you to add these information. Please have a look at this example or at the F-Droid docs or fastlane docs.
After you have commited these files to your repo and tagged a new version, you need to remove the Description and Summary from the metadata file in the F-Droid Data repo.