Disclaimer in README.md about non-production readiness

Can we add a disclaimer in the README that NSS should not be used with production data? I've found that it's used in production and marketed as a "secure" place to store your data.

There's already following disclaimer in the index.html file:

This is a prototype implementation of a Solid server. It is a fully functional server, but there are no security or stability guarantees.

I think it serves the purpose of a prototype server well. But I think we should copy this disclaimer to the README to make clear expectations.

(And while it would be nice to get it production ready, I suppose there are not enough resources to make it secure in the near future)

Vergleiche den bestehenden Haftungsausschluss in index.html mit README.md, beginnend bei der Einleitung oder Projektbeschreibung in README. Als erledigt gilt die Aufgabe, wenn README eindeutig dieselbe Warnung bezüglich Prototyp-, Sicherheits- und Stabilitätsrisiken enthält; es sind keine Codeänderungen vorgesehen.