docs: add Colab badge to Google ADK tracing notebook for easier access

Author: viniciusdsmello

examples/tracing/google-adk/google_adk_tracing.ipynb

@@ -4,6 +4,8 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
+    "[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/openlayer-ai/openlayer-python/blob/main/examples/tracing/google-adk/google_adk_tracing.ipynb)\n",
+    "\n",
     "# Google ADK Tracing with Openlayer\n",
     "\n",
     "This notebook demonstrates how to trace Google Agent Development Kit (ADK) agents with Openlayer.\n",