Create MQTT.md with protocol overview and usage examples. Update client/bin/src/main.rs to initialize a Paho MQTT client with environment-configured broker, connect, and publish combined weather and transit data to the ledboard/data topic.
Create MQTT.md with protocol overview and usage examples. Update client/bin/src/main.rs to initialize a Paho MQTT client with environment-configured broker, connect, and publish combined weather and transit data to the ledboard/data topic.