Plane: added a note about the dangers of the FS_GCS_ENABL option

ArduPlane/Parameters.pde

@@ -342,7 +342,7 @@ const AP_Param::Info var_info[] PROGMEM = {
 
     // @Param: FS_GCS_ENABL
     // @DisplayName: GCS failsafe enable
-    // @Description: Enable ground control station telemetry failsafe. Failsafe will trigger after 20 seconds of no MAVLink heartbeat messages
+    // @Description: Enable ground control station telemetry failsafe. Failsafe will trigger after 20 seconds of no MAVLink heartbeat messages. WARNING: Enabling this option opens up the possibility of your plane going into failsafe mode and running the motor on the ground it it loses contact with your ground station. If this option is enabled on an electric plane then either use a separate motor arming switch or remove the propeller in any ground testing.
     // @Values: 0:Disabled,1:Enabled
     // @User: Standard
     GSCALAR(gcs_heartbeat_fs_enabled, "FS_GCS_ENABL", GCS_HEARTBEAT_FAILSAFE),