fix doc demo bug
fix doc demo bug

the service parameter not used.
rnaveiras/etcd,mqliang/etcd,etcd-io/etcd,ajityagaty/etcd,rnaveiras/etcd,rnaveiras/etcd,ajityagaty/etcd,gyuho/etcd,gyuho/etcd,mkumatag/etcd,mqliang/etcd,mkumatag/etcd,etcd-io/etcd,coreos/etcd,ajityagaty/etcd,mqliang/etcd,etcd-io/etcd,mkumatag/etcd,coreos/etcd