For the udp-client example, instruct user to add an entry for a udp based
service.
For tcp-client & udp-client, use the same port in configuration snippet as used
in the comment prior to remove any ambiguity on the port number which needs to
be specified.

Reviewed by: bcr (mentor) wblock (mentor)
Approved by: gavin
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D9830