Doc: Android sensor permissions

The sensors exposed by the Android backend can be read without
requesting any Android permission. The only restriction is the sampling
rate of the accelerometer, gyroscope, and magnetometer, which is capped
at 200 Hz unless the application declares the HIGH_SAMPLING_RATE_SENSORS
permission (Android 12, API level 31).

Document this in the platform specific notes.

Pick-to: 6.12
Change-Id: I1b20741da8330ee9d42cfad4868234a97de30789
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>