Add example of .local name resolution

[hadess]

This would be helpful for applications and libraries that want to add .local name resolution without requiring OS support (NSS configuration, Avahi availability and accessibility).

I'm guessing it involves starting a listen and checking for R_A and R_AAAA type answers in the callback, but I don't know which parameters I'd need to pass to mdns_listen(), and it's been 17 years since I last worked on an mDNS implementation.

[jbkempf]

That's a good point.