message: correct url
  correct broken url for 1) Eager Execution
diff: @@ -5,7 +5,7 @@ operations. Write custom layers, forward passes, and training loops with
  auto&nbsp;differentiation. Start with these notebooks, then read the
  [eager execution guide](../../guide/eager).
  -1. <span>[Eager execution](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/eager/python/examples/notebooks/eager_intro.ipynb){:.external}</span>
  +1. <span>[Eager execution](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/eager/python/examples/notebooks/eager_basics.ipynb){:.external}</span>
  2. <span>[Automatic differentiation and gradient tape](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/eager/python/examples/notebooks/automatic_differentiation.ipynb){:.external}</span>
  3. <span>[Custom training: basics](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/eager/python/examples/notebooks/custom_training.ipynb){:.external}</span>
  4. <span>[Custom layers](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/eager/python/examples/notebooks/custom_layers.ipynb){:.external}</span>
  