Doc: update logging convention
Doc: update logging convention

Update the logging convention as capnslog is replaced by zap.

mkumatag/etcd,etcd-io/etcd,rnaveiras/etcd,ajityagaty/etcd,etcd-io/etcd,mqliang/etcd,rnaveiras/etcd,mqliang/etcd,ajityagaty/etcd,etcd-io/etcd,mqliang/etcd,ajityagaty/etcd,mkumatag/etcd,rnaveiras/etcd,mkumatag/etcd