4.8:33792/zero-takeoff-alt-check

document zero takeoff altitude mission check

Added in ArduPilot/ardupilot#33792. AP_Arming::mission_checks() now
fails arming with "Mission: Zero takeoff altitude" if any takeoff-type
mission command has an altitude of exactly 0, since that's almost
always a forgotten value rather than intentional. Negative altitudes
are not checked.

Added to both the Mission: prose subsection and the main "Pre-Arm
Failure Messages (All vehicle types)" table, matching how the other
Mission: entries (No mission library present, No rally library
present, Missing mission item: xxxx) are each mirrored in the table.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: Hwurzburg

common/source/docs/common-prearm-safety-checks.rst

@@ -218,6 +218,7 @@ Pre-arm checks that are failing will also be sent as messages to the GCS while d
     Yaw (RCx) is not neutral                                RC transmitter's yaw stick is not centered          Move RC yaw stick to center or repeat :ref:`radio calibration <common-radio-control-calibration>`
     Yaw radio max too low                                   RC yaw channel max below 1700                       Repeat the :ref:`radio calibration <common-radio-control-calibration>` procedure or increase :ref:`RC2_MAX<RC2_MAX>` above 1700
     Yaw radio min too high                                  RC yaw channel min above 1300                       Repeat the :ref:`radio calibration <common-radio-control-calibration>` procedure or reduce :ref:`RC1_MIN<RC1_MIN>` below 1300
+    Zero takeoff altitude                                   A takeoff command in the mission has altitude 0     Set a non-zero altitude for the takeoff command
     ======================================================= =================================================== ====================================================
 
 [site wiki="copter"]
@@ -504,6 +505,8 @@ See :ref:`ARMING_MIS_ITEMS<ARMING_MIS_ITEMS>`
 
 **Missing mission item: xxxx**: A required mission items is missing.
 
+**Zero takeoff altitude**: A takeoff command in the mission has an altitude of 0. Set a non-zero altitude for the takeoff command.
+
 Rangefinder:
 ------------