chore(docs): Minor adjustments to the colab (googleapis#161)

1) text-bison is no longer supported, switch to gemini-2.0-flash-001;
2) add allowed node types to restrict the number of different node
   types;

Co-authored-by: Averi Kitsch <[email protected]>

Author: mtyin

docs/graph_store.ipynb

@@ -225,8 +225,10 @@
     "from langchain_experimental.graph_transformers import LLMGraphTransformer\n",
     "from langchain_google_vertexai.llms import VertexAI\n",
     "\n",
-    "llm = VertexAI(model_name=\"text-bison\")\n",
-    "llm_transformer = LLMGraphTransformer(llm=llm)\n",
+    "llm = VertexAI(model_name=\"gemini-2.0-flash-001\")\n",
+    "llm_transformer = LLMGraphTransformer(\n",
+    "    llm=llm, allowed_nodes=[\"Person\", \"Company\", \"Product\"]\n",
+    ")\n",
     "\n",
     "\n",
     "def get_document_from_wiki(query):\n",
@@ -313,7 +315,7 @@
     "INSTANCE = \"\"  # @param {type: \"string\"}\n",
     "DATABASE = \"\"  # @param {type: \"string\"}\n",
     "GRAPH_NAME = \"\"  # @param {type: \"string\"}\n",
-    "USE_FLEXIBLE_SCHEMA = False  # param {type: \"bool\"}"
+    "USE_FLEXIBLE_SCHEMA = False  # @param {type: \"boolean\"}"
    ]
   },
   {