Use relative link for Intro to graphs for Saved model migration guide

Author: 8bitmp3

site/en/guide/migrate/saved_model.ipynb

@@ -655,7 +655,7 @@
         "\n",
         "Signatures are the endpoints of a SavedModel—they tell the user how to run the model and what inputs are needed.\n",
         "\n",
-        "In TensorFlow 1, signatures are created by listing the input and output tensors. In TensorFlow 2, signatures are generated by passing in *concrete functions*. (Read more about TensorFlow functions in the [Introduction to graphs and tf.function](https://www.tensorflow.org/guide/intro_to_graphs) guide.) In short, [a concrete function is generated](https://www.tensorflow.org/guide/intro_to_graphs#polymorphism_one_function_many_graphs) from a `tf.function`:\n",
+        "In TensorFlow 1, signatures are created by listing the input and output tensors. In TensorFlow 2, signatures are generated by passing in *concrete functions*. (Read more about TensorFlow functions in the [Introduction to graphs and tf.function](../guide/intro_to_graphs.ipynb) guide, particularly the _Polymorphism: one Function, many graphs_ section.) In short, a concrete function is generated from a `tf.function`:\n",
         "\n",
         "```python\n",
         "# Option 1: Specify an input signature.\n",