clientv3: document context timeout error with server-side clock skew
// // ctx is canceled by another routine
// } else if err == context.DeadlineExceeded {
// // ctx is attached with a deadline and it exceeded
+// } else if ev, ok := status.FromError(err); ok {
+// code := ev.Code()
+// if code == codes.DeadlineExceeded {
+// // server-side context might have timed-out first (due to clock skew)
+// // while original client-side context is not timed-out yet
+// }
// } else if verr, ok := err.(*v3rpc.ErrEmptyKey); ok {
// // process (verr.Errors)
// } else {
