C.E in docs & examples

[wayslog]

I have an ipv6 address, so that when I try to run cargo run that localhost will get the nth(0) result of "localhost:10000".to_socket_addrs().unwrap() as V6[::10000].

so, when connect to 127.0.0.1:10000 ， the connection will raise an Os Error show me that this IpV4 address has not been listened yet.

there is a work through pull-request like #2 ,but it seems not to deal with the real problem.

fixed plz. personally , I recommend we have the default usage in IpV4, that's so nice .

for my poor English , tks for reading to the end.