Fix indentation for num_generations parameter

In the Previous Commit I didn't add a comma so it broke the json structure. Extremely sorry for that.

Author: miniMagic-beep

notebooks/en/fine_tuning_llm_grpo_trl.ipynb

@@ -499,8 +499,7 @@
         "\n",
         "    # Parameters that control de data preprocessing\n",
         "    max_completion_length=64, # default: 256\n",
-        "    num_generations=4, # default: 8\n"
-        "  
+        "    num_generations=4, # default: 8\n",
         "\n",
         "    # Parameters related to reporting and saving\n",
         "    report_to=[\"tensorboard\"],\n",