docs: notebook loader: change .html to .ipynb (#22407)

Co-authored-by: Erick Friis <erick@langchain.dev>

docs/docs/integrations/document_loaders/jupyter_notebook.ipynb

@@ -8,7 +8,7 @@
     "\n",
     ">[Jupyter Notebook](https://en.wikipedia.org/wiki/Project_Jupyter#Applications) (formerly `IPython Notebook`) is a web-based interactive computational environment for creating notebook documents.\n",
     "\n",
-    "This notebook covers how to load data from a `Jupyter notebook (.html)` into a format suitable by LangChain."
+    "This notebook covers how to load data from a `Jupyter notebook (.ipynb)` into a format suitable by LangChain."
    ]
   },
   {
@@ -31,7 +31,7 @@
    "outputs": [],
    "source": [
     "loader = NotebookLoader(\n",
-    "    \"example_data/notebook.html\",\n",
+    "    \"example_data/notebook.ipynb\",\n",
     "    include_outputs=True,\n",
     "    max_output_length=20,\n",
     "    remove_newline=True,\n",
@@ -42,7 +42,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "`NotebookLoader.load()` loads the `.html` notebook file into a `Document` object.\n",
+    "`NotebookLoader.load()` loads the `.ipynb` notebook file into a `Document` object.\n",
     "\n",
     "**Parameters**:\n",
     "\n",