App dependencies, minimal Android version and requirements

[ericbl]

Please add in the Readme or App document a chapter about android requirements:
a) HW requirements if any
b) minimum Android version where the app can run - testing on old smartphone like on Android 4.4 could be helpful here
c) any external SW dependencies.

[steveacab]

Min Android version is 7.0 according by SDK 24 min required.

[goebelUB]

Correct, it was originally Android 7 / API 24, we've since lowered it to Android 6 / API 23.

The minimum Android version is now documented in the readme. I won't document the other dependencies, as they are either obvious (your phone needs a camera to scan QR codes) or redundant (documented in the build.gradle for devs and in-app imprint for users, so maintaining a third place would be unnecessary extra effort).