Need sensor calibration screens from ArduPilot

[hamishwillee]

As per #80 (comment)

We need new screenshots on ArduPilot to cover:

• For places which show you compass settings, you can have up to three compasses. (confirm only 2 compasses on PX4)
• Level Horizon for ArduPilot is slightly different. No option for orientation change.
• Additional AirSpeed cal for ArduPilot if needed.

@DonLakeFlyer To provide these, as I can't replicate (or perhaps even better, if this can be mocked explain exactly how and I can add that to our mocklink docs.)