Fix typo in Colab link (#4276)

Author: sergiopaniego

examples/notebooks/grpo_qwen3_vl.ipynb

@@ -8,7 +8,7 @@
       "source": [
         "# GRPO Qwen3-VL with QLoRA using TRL\n",
         "\n",
-        "[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/trl/blob/main/notebooks/grpo_qwen3_vl.ipynb)\n",
+        "[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/trl/blob/main/examples/notebooks/grpo_qwen3_vl.ipynb)\n",
         "\n",
         "![trl banner](https://huggingface.co/datasets/trl-lib/documentation-images/resolve/main/trl_banner_dark.png)\n",
         "\n",