Rocketchat modify .htaccess

Hi,

maybe it is simple to change, but how can I modify the .htaccess for rocketchat? Are there any univention templates I have to modify or do I have to login to the docker container (but then can’t be any permanent change, right?)?

More specific: I need to set the http-header x-frame-options for allowing another domain website to integrate rocketchat

Mastodon