Added STICK_CENTER_ONCE to mc_airmode_type_help message

_locales/en/messages.json

@@ -3290,7 +3290,8 @@
         "message": "Airmode handling type"
     },
     "mc_airmode_type_help": {
-        "message": "Defines the Airmode state handling type for Multirotors. <br />Default STICK_CENTER is the classical approach in which Airmode is always active if enabled, but when the throttle is low and ROLL/PITCH/YAW sticks are centered, Iterms is not allowed to grow (ANTI_WINDUP). <br />THROTTLE_THRESHOLD is the Airmode behavior known from Betaflight. In this mode, Airmode is active as soon THROTTLE position is above <i>mc_airmode_threshold</i> and stays active until disarm. ANTI_WINDUP is never triggered. For small Multirotors (up to 7-inch propellers) it is suggested to switch to THROTTLE_THRESHOLD since it keeps full stabilization no matter what pilot does with the sticks. Fixed Wings always use STICK_CENTER mode."
+        "message": "Defines the Airmode state handling type for Multirotors. <br />Default STICK_CENTER is the classical approach in which Airmode is always active if enabled, but when the throttle is low and ROLL/PITCH/YAW sticks are centered, Iterms is not allowed to grow (ANTI_WINDUP). <br />STICK_CENTER_ONCE works like STICK_CENTER, but only until the
+ first time THROTTLE is not low and ROLL/PITCH/YAW sticks are moved. After that, ANTI_WINDUP is deactivated until next arm. Useful for airplanes. <br />THROTTLE_THRESHOLD is the Airmode behavior known from Betaflight. In this mode, Airmode is active as soon THROTTLE position is above <i>mc_airmode_threshold</i> and stays active until disarm. ANTI_WINDUP is never triggered. For small Multirotors (up to 7-inch propellers) it is suggested to switch to THROTTLE_THRESHOLD since it keeps full stabilization no matter what pilot does with the sticks. Fixed Wings always use STICK_CENTER mode."
     },
     "mc_airmode_threshold": {
         "message": "Airmode Throttle threshold"