Land detector: Update param metadata

This helps with param transfers and will hide these params by default from the user.

src/modules/land_detector/land_detector_params.c

@@ -38,6 +38,8 @@
  * Flight time in microseconds = (LND_FLIGHT_T_HI << 32) | LND_FLIGHT_T_LO.
  *
  * @min 0
+ * @volatile
+ * @category system
  * @group Land Detector
  *
  */
@@ -50,6 +52,8 @@ PARAM_DEFINE_INT32(LND_FLIGHT_T_HI, 0);
  * Flight time in microseconds = (LND_FLIGHT_T_HI << 32) | LND_FLIGHT_T_LO.
  *
  * @min 0
+ * @volatile
+ * @category system
  * @group Land Detector
  *
  */