Adding extra information in the market app description

[JuancaG05]

Checking feedback in the Android app, I realise there are some users facing problems with 2FA and the Android (and iOS AFAIK) app. They say they activate the feature in the web, installing it from the market, and then they cannot login in the app. That's the expected behaviour because we have no support for 2FA nowadays, but users don't have information about this at all.

My proposal is, if possible, add a sentence like
NOTE: no support for Android and iOS ownCloud apps
in the description of the app in the market:

Or at least, add a link to this documentation, so that users know which possibilities they have when using 2FA and the mobile apps.