Update submissions.json

Command used:

`lighteval accelerate "model_name=iamgroot42/smollm3-Custom-SFT" "lighteval|gsm8k|0|0" --push-to-hub --results-org iamgroot42`

submissions.json

@@ -6,6 +6,13 @@
             "chapter": "1",
             "submission_date": "2025-09-02",
             "results-dataset": "smol-course/details_HuggingFaceTB__SmolLM3-3B_private"
-        }
+        },
+        {
+            "username": "iamgroot42",
+            "model_name": "smollm3-Custom-SFT",
+            "chapter": "1",
+            "submission_date": "2025-09-13",
+            "results-dataset": "iamgroot42/details_iamgroot42__smollm3-Custom-SFT"
+        },
     ]
 }