docs: update langchain-unstructured docs (#24935)

- **Description:** The UnstructuredClient will have a breaking change in
the near future. Add a note in the docs that the examples here may not
use the latest version and users should refer to the SDK docs for the
latest info.

docs/docs/integrations/document_loaders/unstructured_file.ipynb

@@ -31,7 +31,8 @@
     "### Local Partitioning (Optional)\n",
     "\n",
     "By default, `langchain-unstructured` installs a smaller footprint that requires\n",
-    "offloading of the partitioning logic to the Unstructured API.\n",
+    "offloading of the partitioning logic to the Unstructured API, which requires an `api_key`. For\n",
+    "partitioning using the API, refer to the Unstructured API section below.\n",
     "\n",
     "If you would like to run the partitioning logic locally, you will need to install\n",
     "a combination of system dependencies, as outlined in the \n",
@@ -358,8 +359,9 @@
     "Partitioning with the Unstructured API relies on the [Unstructured SDK\n",
     "Client](https://docs.unstructured.io/api-reference/api-services/sdk).\n",
     "\n",
-    "Below is an example showing how you can customize some features of the client and use your own\n",
-    "`requests.Session()`, pass in an alternative `server_url`, or customize the `RetryConfig` object for more control over how failed requests are handled."
+    "Below is an example showing how you can customize some features of the client and use your own `requests.Session()`, pass in an alternative `server_url`, or customize the `RetryConfig` object for more control over how failed requests are handled.\n",
+    "\n",
+    "Note that the example below may not use the latest version of the UnstructuredClient and there could be breaking changes in future releases. For the latest examples, refer to the [Unstructured Python SDK](https://docs.unstructured.io/api-reference/api-services/sdk-python) docs."
    ]
   },
   {