Add a "monitor-connection-files" config option, which can be set to
"false" to disable automatic reloading of connections on file change.
To go with this, add a new ReloadConnections method on
o.fd.NM.Settings that can be used to manually reload connections, and
add an nm-cli command to call it.
DocBook is not my favorite thing in the world, but it's
<lots-of-emphasis>far</lots-of-emphasis> saner than troff. Some style
parts cribbed from systemd.
This is preparatory work for actually improving the content of the
man pages.
