release ChatBot example

Author: zsdonghao

README.md

@@ -18,6 +18,7 @@
 TensorLayer is a deep learning and reinforcement learning library based on [Google TensorFlow](https://www.tensorflow.org). It provides rich data processing, model training and serving modules to help researchers and engineers build practical machine learning workflows.  
 
 # What's New
+* New example [Chatbot in 200 lines of code](https://github.com/zsdonghao/seq2seq-chatbot) for [Seq2Seq](http://tensorlayer.readthedocs.io/en/latest/modules/layers.html#simple-seq2seq).
 * Release [ROI layer](http://tensorlayer.readthedocs.io/en/latest/modules/layers.html#roi-layer) for Object Detection.
 * Release [Sub-pixel Convolution 1D](http://tensorlayer.readthedocs.io/en/latest/modules/layers.html#d-supixel-convolutional) for Audio Super-resolution.
 * Release [Flickr dataset loader](http://press.liacs.nl/mirflickr/mirdownload.html), see [load_flickr25k](http://tensorlayer.readthedocs.io/en/latest/modules/files.html#flickr25k) and [load_flickr1M](http://tensorlayer.readthedocs.io/en/latest/modules/files.html#flickr1m).

docs/user/example.rst

@@ -35,6 +35,7 @@ Natural Language Processing
  - Restore Embedding matrix. Restore a pre-train embedding matrix, see `tutorial_generate_text.py <https://github.com/zsdonghao/tensorlayer/blob/master/example/tutorial_generate_text.py>`_.
  - Text Generation. Generates new text scripts, using LSTM network, see `tutorial_generate_text.py <https://github.com/zsdonghao/tensorlayer/blob/master/example/tutorial_generate_text.py>`_.
  - Chinese Text Anti-Spam by `pakrchen <https://github.com/pakrchen/text-antispam>`_.
+ - New example `Chatbot in 200 lines of code <https://github.com/zsdonghao/seq2seq-chatbot>`_ for `Seq2Seq <http://tensorlayer.readthedocs.io/en/latest/modules/layers.html#simple-seq2seq>`_.
 
 Adversarial Learning
 ========================

tensorlayer/layers.py

@@ -4868,7 +4868,7 @@ class Seq2Seq(Layer):
     See `Model <https://camo.githubusercontent.com/242210d7d0151cae91107ee63bff364a860db5dd/687474703a2f2f6936342e74696e797069632e636f6d2f333031333674652e706e67>`_
     and `Sequence to Sequence Learning with Neural Networks <https://arxiv.org/abs/1409.3215>`_.
 
-    - Please check the example `Twitter Chatbot <>`_.
+    - Please check the example `Chatbot in 200 lines of code <https://github.com/zsdonghao/seq2seq-chatbot>`_.
     - The Author recommends users to read the source code of :class:`DynamicRNNLayer` and :class:`Seq2Seq`.
 
     Parameters