inetd.8: Remove the enumeration of examples

The user can trivially see the list of examples in /etc/inetd.conf
by looking at the file, so there's no need to include an entire
paragraph in the manual enumerating the examples which are provided.

MFC after: 3 days
Reviewed by: 0mp
Sponsored by: https://www.patreon.com/bsdivy
Differential Revision: https://reviews.freebsd.org/D52740