Document new settings for external mag alignment

docs/Cli.md

@@ -230,6 +230,9 @@ Re-apply any new defaults as desired.
 |  align_board_roll  | 0 | Arbitrary board rotation in degrees, to allow mounting it sideways / upside down / rotated etc |
 |  align_board_pitch  | 0 | Arbitrary board rotation in degrees, to allow mounting it sideways / upside down / rotated etc |
 |  align_board_yaw  | 0 | Arbitrary board rotation in degrees, to allow mounting it sideways / upside down / rotated etc |
+|  align_mag_roll  | 0 | Set the external mag alignment on the roll axis (in 0.1 degree steps). If this value is non-zero, the compass is assumed to be externally mounted and both the board and on-board compass alignent (align_mag) are ignored. See also align_mag_pitch and align_mag_yaw. |
+|  align_mag_pitch  | 0 | Same as align_mag_roll, but for the pitch axis. |
+|  align_mag_yaw  | 0 | Same as align_mag_roll, but for the yaw axis. |
 |  gyro_hardware_lpf  | 42HZ | Hardware lowpass filter for gyro. Allowed values depend on the driver - For example MPU6050 allows 10HZ,20HZ,42HZ,98HZ,188HZ,256Hz (8khz mode). If you have to set gyro lpf below 42Hz generally means the frame is vibrating too much, and that should be fixed first. |
 |  moron_threshold  | 32 | When powering up, gyro bias is calculated. If the model is shaking/moving during this initial calibration, offsets are calculated incorrectly, and could lead to poor flying performance. This threshold means how much average gyro reading could differ before re-calibration is triggered. |
 |  imu_dcm_kp  | 2500 | Inertial Measurement Unit KP Gain for accelerometer measurements |