add documentation on robot arm

[dsmits]

Integrate stefans comments:
The arm receives device-str and position-int for Pick/Place/Move or anything LabwareTransferManipulator feature (this unfortunately starts counting at 1 🙁 which I account for in my wrappers). By default, that is converted as f"{device}{position}" to a position in the position graph. You can change that by overwriting

site_to_position_identifier(self, device: str, slot: int) -> str:

which is a method of RoboInterface.

[dsmits]

There should be a whole section about location mapping. The locations are relevant in multiple places.

It is also important that the lab configuration (the yaml file) is uploaded to the platform_status_db database.