Add Descriptors

[solara404]

Fix: #27

[aaumar25]

Lets work out together the description before merging it.

[aaumar25]

I think now I understand what is hall_sensor.position.on is. It describe the carrier position relative to zero position when triggering the alarm state of the specified hall sensor.
forward: Carrier position when a carrier is moving forward and trigger alarm state of the hall sensor.
backward: Carrier position when a carrier is moving backward and trigger alarm state of the hall sensor.

I will confirm this behavior in the simulation first and update this state by myself later.