Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1894
Because the configuration file is now mounted as readonly and maubot tries to update it on start,
we get this warning:
> Failed to create tempfile to write updated config to disk: [Errno 30] Read-only file system: '/config/tmpfa8vcb3y.yaml'
It doesn't seem to cause issues though.
Because the configuration is no longer overwritten on every bot start, each
next Ansible run should no longer overwrite it again and report a
"changed" task.
* Make interface hidden behind proxy by default
* Remove expose option and replace with http_bind_port
Reasoning: This is a similar binary trigger but allows to bin not on all interfaces
* Clarify maubot admin purpose
* Remove unnecessary edif
* Extend docs to prevent common misconceptions
* Make http_bind_port singular, do not allow multiple values
* Make optional again
