[2pt] stream support was added to net.box

[TarantoolBot]

Product: Tarantool
Since: 2.10.0-beta1
Root document: https://www.tarantool.io/en/doc/latest/reference/reference_lua/net_box/
SME: @ expert to ask for more information
Peer reviewer: @ EvgenyMekhanik

Details

In "net.box", stream is an object over connection that
has the same methods, but all requests from it sends
with non-zero stream ID. Stream ID is generated on the
client automatically. Simple example of stream creation
using net.box:

stream = conn:new_stream()
-- all connection methods are valid, but send requests
-- with non zero stream_id.

Requested by @ EvgenyMekhanik in tarantool/tarantool@0084f90.

Related to #2307

[art-dr]

"…stream is an object over connection that
has the same methods…" — over or in?

[patiencedaur]

Add a short description of streams and an example to the net.box page. Consider how it's done in Binary protocol.