Documentation for MulticastDNS setting suggests it should be part of the
main iwd configuration file. See man iwd.config. However, in reality
the setting was being pulled from the network provisioning file instead.
The latter actually makes more sense since systemd-resolved has its own
set of global defaults. Fix the documentation to reflect the actual
implementation.
When using iwd.conf:[General].EnableNetworkConfiguration=true, it is not
possible to configure systemd.network:[Network].MulticastDNS= as
systemd-networkd considers the link to be unmanaged. This patch allows
iwd to configure that setting on systemd-resolved directly.
The docs just specified what a IP prefix looks like, not an
actual example. Though its not recommended to just copy paste
blindly, its still useful to have some value in the man pages
that actually works if someone just wants to get a DHCP server
working.