Create flowchart for MQTT Task in sw_architecture.md

[patrickanguyen]

Description

The flowchart for the MQTT Task should be documented in sw_architecture.md before development. Add a flowchart diagram using mermaid markdown. You can use this website to create the flowcharts, then copy them onto the markdown file.

The MQTT task is responsible for publishing the sensor data to the MQTT broker. The MQTT task will receive the sensor values from a thread-safe queue from the different tasks. The MQTT task will wait for the sensor data from the queue. If the data is not received in time, it will set the sensor value to an error code and continue.

This is some documentation about FreeRTOS queue to help conceptualize how queues work in practice.

Please outreach if you need any help with this issue. This is a bit more complicated than the rest of the tasks.

Requirements

• Should include the initialization of sensor step
• Include a scenario for sensors failing
• Make sure the design is robust as possible