Fix a dead link to dynamic_rnn

Author: akimach

tensorflow_fold/g3doc/quick.ipynb

@@ -291,7 +291,7 @@
  "cell_type": "markdown",
  "metadata": {},
  "source": [
- "Right, but you've done the TF [RNN Tutorial](https://www.tensorflow.org/tutorials/recurrent/) and even poked at [seq-to-seq](https://www.tensorflow.org/tutorials/seq2seq/). You're a wizard with [dynamic rnns](https://www.tensorflow.org/api_docs/python/nn/recurrent_neural_networks#dynamic_rnn). What does Fold offer?\n",
+ "Right, but you've done the TF [RNN Tutorial](https://www.tensorflow.org/tutorials/recurrent/) and even poked at [seq-to-seq](https://www.tensorflow.org/tutorials/seq2seq/). You're a wizard with [dynamic rnns](https://www.tensorflow.org/api_docs/python/tf/nn/dynamic_rnn). What does Fold offer?\n",
  "\n",
  "Well, how about jagged arrays?"
  ]