Switch Companion app link to official F-Droid repo

app/_index.md

@@ -13,13 +13,9 @@ title: Companion App
 
 # Android / F-Droid releases
 
-You can find the latest release of the Companion App in the CCC F-Droid repository.
-
-To add the repository, open F-Droid, go to Settings -> Repositories -> +.
-
-[Link](https://fdroid.gitlab.io/ccc/)
-[![https://fdroid.gitlab.io/ccc/](https://fdroid.gitlab.io/ccc/icon.png)](https://fdroid.gitlab.io/ccc/)
+You can find the latest release of the Companion App in the F-Droid repository:
 
+[Companion App for the card10 Chaos Communication Camp badge](https://f-droid.org/app/de.ccc.events.badge.card10)
 
 # iOS Testflight builds