Add H1 and intro back into Gemma+LangChain notebook (#318)

* add H1 and intro back in

* nbfmt

site/en/gemma/docs/integrations/langchain.ipynb

@@ -50,6 +50,19 @@
         "</table>"
       ]
     },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "3acc8f3d1408"
+      },
+      "source": [
+        "# Get started with Gemma and LangChain\n",
+        "\n",
+        "This tutorial shows you how to get started with [Gemma](https://ai.google.dev/gemma/docs) and [LangChain](https://python.langchain.com/docs/get_started/introduction), running in Google Cloud or in your Colab environment. Gemma is a family of light-weight, state-of-the-art open models built from the same research and technology used to create the Gemini models. LangChain is a framework for building and deploying context-aware applications backed by language models.\n",
+        "\n",
+        "**Note:** This tutorial runs on A100 GPU in Google Colab. Free Colab hardware acceleration is *insufficient* to run all the code."
+      ]
+    },
     {
       "cell_type": "markdown",
       "metadata": {