add BBL SERVO logging option

locale/en/messages.json

@@ -1238,16 +1238,16 @@
     "configurationGimbal": {
         "message": "Serial Gimbal"
     },
-    "configurationGimbalSensitivity": { 
+    "configurationGimbalSensitivity": {
         "message":"Gimbal sensitivity"
     },
-    "configurationGimbalPanChannel": { 
+    "configurationGimbalPanChannel": {
         "message":"Pan channel (yaw)"
     },
-    "configurationGimbalTiltChannel": { 
+    "configurationGimbalTiltChannel": {
         "message":"Tilt channel (pitch)"
     },
-    "configurationGimbalRollChannel": { 
+    "configurationGimbalRollChannel": {
         "message":"Roll channel"
     },
     "configurationHeadtracker": {
@@ -5218,6 +5218,9 @@
     "BLACKBOX_FEATURE_GYRO_PEAKS_YAW": {
         "message": "Gyro Noise peak freq. Yaw"
     },
+    "BLACKBOX_FEATURE_SERVOS": {
+        "message": "Servos output"
+    },
     "axisRoll": {
         "message": "Roll"
     },

tabs/onboard_logging.js

@@ -38,6 +38,7 @@ TABS.onboard_logging.initialize = function (callback) {
         "BLACKBOX_FEATURE_GYRO_PEAKS_ROLL",
         "BLACKBOX_FEATURE_GYRO_PEAKS_PITCH",
         "BLACKBOX_FEATURE_GYRO_PEAKS_YAW",
+        "BLACKBOX_FEATURE_SERVOS",
     ];
 
     if (GUI.active_tab != 'onboard_logging') {