Please add German documentation reference on arpeggio brackets with connectArpeggios.

[Malte Meyn]

> I'm not top posting.

The English documentation writes
“The simple way of setting parenthesis-style arpeggio brackets does not work
for cross-staff arpeggios; see Cross-staff stems.”

This reference to the section about cross-staff stems isn’t present in the
German notation reference:
“Die Arpeggios im Klammer-Stil funktionieren nicht über mehrere Notensysteme.”
This sounds like “it isn’t possible at all” to me so I first didn’t even try
to find a solution ;)