added detailed comment to explain the difference between Lock and LockWithoutHook
added detailed comment to explain the difference between Lock and LockWithoutHook

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