Update README.md
Fix 404 page not found
@@ -53,7 +53,7 @@ and you can export your Keras models to run in the browser or on a mobile device
The core data structures of Keras are __layers__ and __models__.
The simplest type of model is the [`Sequential` model](/guides/sequential_model/), a linear stack of layers.
-For more complex architectures, you should use the [Keras functional API](/guides/functional_api/),
+For more complex architectures, you should use the [Keras functional API](https://keras.io/guides/functional_api/),
which allows you to build arbitrary graphs of layers or [write models entirely from scratch via subclassing](/guides/making_new_layers_and_models_via_subclassing/).
Here is the `Sequential` model:
