Request for better accelerometer calib description

ArduPlane 3.0.1
APM_Planner 2.0.8

For me it's unclear what differs the first step in 'Calibrate Accelerometer' (acc1) from 'Level Accelerometer' (acc2).

UAV level or APM level? There seem to be inconsistency in the description text in the gui.

My guess is that
- acc1 should have the APM placed level on each side.
- acc2 should have the UAV placed level, but the APM could be on an angle, if for example mounted on top of a sloping wing.

Compare the APM Planner GUI text for “Calibrate Accelerometer” (acc1) and “Level Accelerometer” (acc2), using the issue’s orientation questions as the starting point. Done means the descriptions clearly distinguish whether the APM or UAV should be level and no longer appear inconsistent.

Written by the indexing model from the issue text.