common.xml: add leak sensor to SYS_STATUS_EXTENDED (mavlink#2427)

Author: ES-Alexander

message_definitions/v1.0/common.xml

@@ -205,6 +205,9 @@
       <entry value="1" name="MAV_SYS_STATUS_RECOVERY_SYSTEM">
         <description>0x01 Recovery system (parachute, balloon, retracts etc)</description>
       </entry>
+      <entry value="2" name="MAV_SYS_STATUS_SENSOR_LEAK">
+        <description>0x02 Leak detection</description>
+      </entry>
     </enum>
     <enum name="MAV_FRAME">
       <description>Coordinate frames used by MAVLink. Not all frames are supported by all commands, messages, or vehicles.