Update config.json

Author: tongkiat

config.json

@@ -444,6 +444,16 @@
         "math",
         "string"
       ]
+    },
+    {
+      "slug": "sublist",
+      "uuid": "ac954921-31e4-4c8d-8125-9d44a8c1baba",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 2,
+      "topics": [
+        "list"
+      ]
     }
   ]
 }