Owncloud 9.1 - configure trusted_domain

How can I configure the trusted_domain-setting of the docker-version of owncloud 9.1 with ucs 4.1-4?

In the docker-instance (startet with ‘univention-app shell owncloud82’) what editor is installed? If I installed ‘nano’ then following error come up:

root@owncl-41661632:/# nano /var/www/owncloud/config/config.php
Error opening terminal: unknown.

I found that the editor ‘VIM’ is available in docker and can be used to change the config/config.php