Mention cordova shortcomings/known issues

[nickve28]

It would be nice if we could describe known issue we've encountered in cordova, like websql/indexeddb being cleared.

This is never mentioned anywhere in the cordova docs as far as I've found https://cordova.apache.org/docs/en/latest/cordova/storage/storage.html

[pascalw]

@nickve28 good point. As we discussed recently we should ship nativeStorage support out of the box, so this is no longer an issue at all.