Curl example should use unbuffered connection

[PetrGlad]

page docs/using/consuming-events.html should use unbuffered curl connection:

curl -N -v http://localhost:8080/event-types/order_received/events

Or, alternatively --no-buffer instead of -N. Without it, latest messages might not be shown until buffer is full. This is especially acute problem with infrequent events.
To be precise, you will see every batch eventually, since Nakadi sends keepalive messages. Once your buffer is filled with those keepalive messages you'll see all real batches. I still hope that this is not intended to be a user's patience test.