Show how deadline can be set

[stanley-cheung]

Show how we can set a deadline header for each RPC. The value should be a Unix timestamp, in milliseconds. The format should be the same as a gRPC Node client.

var deadline = new Date();
deadline.setSeconds(deadline.getSeconds() + 1);

client.sayHelloAfterDelay(request, {deadline: deadline.getTime()},
  (err, response) => {
    // err will be populated if the RPC exceeds the deadline
    ...
  });