docs/MQTT: remove outdated paaragraphs

docs/MQTT.md

@@ -27,15 +27,3 @@ Remaining limitations:
  - No username/password support
  - No TLS (mqtts) support
  - Naive EAGAIN handling won't handle split messages
-
-## Work
-
-1. Write a mqtt server for the test suite
-2. Create a few tests verifying the existing mqtt functionality
-3. Work on fixing some of the worst limitations - with accompanying tests
-4. Consider replacing the client-side MQTT code with wolfMQTT
-
-## Credits
-
-The initial MQTT patch was authored by Björn Stenberg. This work is built upon
-that patch and has been expanded since.