Update Remote Settings Server docs to reflect Drive Data changes

The Remote Settings Server has now been renamed to "Middleware". While there's a ticket to track the Companion App documentation work (AUTOSUITE-920), this ticket is for the Conceptual documentation as well as the "Drive Data" related content.

Key poinst:

• Developers can update the simulation.qml file and drive-data.yaml file to modify its appearance and experience. Need to rebuild Neptune 3 after that to view their changes.
• The Drive Data feature uses a simulation backend so, now when you start Neptune 3, you will see the data update itself; it's no longer static.