Remove contradicting geofence parameter description

The flight termination action on geofence violation is described as only trigger, when the corresponding circuit breaker is not disabled. However, the description of the circuit breaker states, that the geofence action is not depedning on this circuit breaker. The implementation follows the description of the circuit breaker. Hence the GF_ACTION description is adapted.

src/modules/navigator/geofence_params.c

@@ -48,9 +48,6 @@
  *
  * Note: Setting this value to 4 enables flight termination,
  * which will kill the vehicle on violation of the fence.
- * Due to the inherent danger of this, this function is
- * disabled using a software circuit breaker, which needs
- * to be reset to 0 to really shut down the system.
  *
  * @min 0
  * @max 5