Update guided mode moving example and guide for MAV_FRAME_BODY_OFFSET_NED #354
Description
The existing guided-set-speed-yaw-demo example documentation around vehicle movement is "mostly" correct. The example uses MAV_FRAME_BODY_NED and should AFAIK work as expected - navigate relative to the home position.
However the documentation states that the frame is ignored in SET_POSITION_TARGET_LOCAL_NED - from AC 3.3 this is no longer the case. Now you can set position and velocity relative to your vehicle heading etc based on the frame type. This can be very convenient for driving the vehicle!
Upshot, we need to look at the existing example and documentation and see if we can improve it.