This uses nginx' server-side includes, so each domain configured by
`__jitsi_meet_domain` can have its own customisation.
Note that the file customisation file must exist for each domain,
`__jitsi_meet_domain` takes care of that already.
Sponsored by: camilion.eu, eXO.cat
with this, admins can take advantage of e.g. matomo to have some usage
statistics.
The parameter defaults to `disabled: true`, which is the most privacy-friendly!
Sponsored by: camilion.eu