Update app store entry

[joshtrichards]

The app store entry is pretty bare bones. A lot of effort has gone into E2EE across @nextcloud. Let's show that clearly in one of the places that new potential users (and previous ones re-installing) interact with the most.

• Screenshot
  • The existing screenshot only shows an E2EE listed folder in the WebUI where it's not accessible
  • Consider adding screenshots of Admin or Personal settings sections and/or client apps to give it more life
• Body (text) should be expanded
  • An up-to-date basic introduction (i.e. use the GitHub description for the app in the upper right or the one in the README)
  • Possibly add short abbreviated Installation and/or Usage and/or Troubleshooting overview/instructions
  • Possible some excerpts from - or an outright abbreviated version - of the repo README

[ChojinDSL]

Wholeheartedly agree. The current state is a complete mess. The documentation/communication on this is either confusing, misleading or flat out wrong.
It's not clear how you are supposed to achieve any kind of E2EE workflow. The documentation claims that you can share encrypted folders with single users. This is NOT the case. Encrypted file drop doesn't work.