Copter: update thrust loss check comments

Co-authored-by: Peter Hall <[email protected]>

ArduCopter/crash_check.cpp

@@ -97,7 +97,7 @@ void Copter::crash_check()
 }
 
 // thrust_loss_check - returns true when the aircraft detects for 1 second that it is:
-//                      above 90% thrust,
+//                      above 90% demanded thrust or high thrust saturation,,
 //                      less than 15 degrees lean angle target,
 //                      less than 30 degrees of attitude error,
 //                      is descending.