docs(client): clarify HttpConnector::new_with_resolver doc (#2255)
docs(client): clarify HttpConnector::new_with_resolver doc (#2255)

link to hyper::client::connect::dns, closes #2254
hyperium/hyper,tshepang/hyper,tshepang/hyper,hyperium/hyper,hyperium/hyper,tshepang/hyper