chore(doc): remove trailing comma in JSON (#2979)

docs/usage/guides/visual/system-tray.md

@@ -13,7 +13,7 @@ Configure the `systemTray` object on `tauri.conf.json`:
   "tauri": {
     "systemTray": {
       "iconPath": "icons/icon.png",
-      "iconAsTemplate": true,
+      "iconAsTemplate": true
     }
   }
 }