/examples folder is out-of-date

[phillip-stephens]

With IPv6 being added, the requirement to give a Resolver a correct IP local address, name servers, etc was added. Without proper config, it will fatally error.

I didn't update the examples when I merged that in and they now do not work:

~/zdns/examples/single_lookup on  phillip/353-multiple-modules! ⌚ 15:46:48
$ go run simple.go 
FATA[0000] Error initializing resolver: invalid resolver config: must have at least one external IPv4 name server if IPv4 mode is enabled 
exit status 1

Should be a quick fix, but I'd like to add some sort of unit test or something that CI will fail if we break these, otherwise I know this'll happen again.