Add rangefinder distance to OSD

_locales/en/messages.json

@@ -3082,6 +3082,9 @@
     "osdSettingMainVoltageDecimals": {
         "message": "Main voltage decimals"
     },
+    "osdElement_OSD_RANGEFINDER": {
+        "message": "Rangefinder distance"
+    },
     "osdSettingPLUS_CODE_DIGITS_HELP": {
         "message": "Precision at the equator: 10=13.9x13.9m; 11=2.8x3.5m; 12=56x87cm; 13=11x22cm."
     }, 

tabs/osd.js

@@ -963,6 +963,11 @@ OSD.constants = {
                         }
                         return FONT.embed_dot('-0.5') + FONT.symbol(SYM.M_S);
                     }
+                },
+                {
+                    name: 'OSD_RANGEFINDER',
+                    id: 120,
+                    preview: "2" + FONT.symbol(SYM.DIST_KM)
                 }
             ]
         },