Configuration example for a repmgr "witness host"

I am trying to do my first install of repmgr for PostgreSQL 14.

I have a working “master / slave” relationship.

My hope was to configure a “witness host” that is not part of the “cluster”.

The example that I’m working from is here. 

https://www.enterprisedb.com/postgres-tutorials/how-implement-repmgr-postgresql-automatic-failover

At step 10, the master and slave have already been configured.

There seems to be nothing in the document to indicate what needs to be in the “witness host” configuration file to monitor the master / slave nodes.

Any help is much appreciated.