[Doc]fix ondisk_dataset_homograph.ipynb (#7258)

notebooks/stochastic_training/ondisk_dataset_homograph.ipynb

@@ -291,7 +291,7 @@
         "print(f\"LP val negative dsts are saved to {lp_val_neg_dsts_path}\\n\")\n",
         "\n",
         "lp_test_node_pairs_path = os.path.join(base_dir, \"lp-test-node-pairs.npy\")\n",
-        "lp_test_node_pairs = edges[-num_tests, :]\n",
+        "lp_test_node_pairs = edges[-num_tests:, :]\n",
         "print(f\"Part of test node pairs for link prediction: {lp_test_node_pairs[:3]}\")\n",
         "np.save(lp_test_node_pairs_path, lp_test_node_pairs)\n",
         "print(f\"LP test node pairs are saved to {lp_test_node_pairs_path}\\n\")\n",