Is your feature request related to a problem? Please describe.
It currently seems to be hard or impossible to use custom fonts when using the built-in Nextcloud Office

Describe the solution you'd like
In 'Administration > Nextcloud Office > Extra Fonts' I’ve uploaded the fonts. This works fine. On that page it says:

Make sure to set this URL: https://<MY_URL>/apps/richdocuments/settings/fonts.json in the coolwsd.xml file of your Collabora Online server to ensure the added fonts get loaded automatically.

I run Nextcloud via Docker. Directly editing the file in the container doesn’t seem to persist after a restart. I tried to mount coolwsd.xml in my docker-compose.yml, but Collabora then doesn’t start (Could not establish connection to the Collabora Online server. is shown in the Nextcloud Office settings).

I see two solutions:

• Allow coolwsd.xml to be mounted or configured in docker-compose.yml
• Automatically configure coolwsd.xml with the URL (that seems to make te most sense for the built-in version right?)