MQTT documentation is missing on readme.io

[Denis Magda]

Hi Raul,

I've noted that there is no documentation available for MQTT streamer on
readme.io.

Since you know the best how it works would you mind adding this [1]?

If you are lack of time then let us know.

[1] https://issues.apache.org/jira/browse/IGNITE-2411

--
Denis