Update README.md

Author: xiaohu2015

README.md

@@ -20,7 +20,7 @@ Note: the project aims at imitating the well-implemented algorithms in [Deep Lea
 You can find more practical examples with tensorflow here:
 - CNN for setence classification [[self](https://github.com/xiaohu2015/DeepLearning_tutorials/tree/master/examples/cnn_setence_classification)] [[blog](http://www.wildml.com/2015/12/implementing-a-cnn-for-text-classification-in-tensorflow/)] [[paper](https://arxiv.org/pdf/1408.5882v2.pdf)]
 - RNN for language model [[self](https://github.com/xiaohu2015/DeepLearning_tutorials/tree/master/examples/rnn_language_model)] [[blog](http://www.wildml.com/2015/09/recurrent-neural-networks-tutorial-part-2-implementing-a-language-model-rnn-with-python-numpy-and-theano/)] [[blog_cn](http://blog.csdn.net/xiaohu2022/article/details/54578013)]
-- LSTM for language model (PBT data) [[self](https://github.com/xiaohu2015/DeepLearning_tutorials/tree/master/examples/lstm_model_ptb)] [[tutorial](https://www.tensorflow.org/versions/r0.12/tutorials/recurrent/index.html#recurrent-neural-networks)] [[paper](https://arxiv.org/pdf/1409.2329.pdf)]
+- LSTM for language model (PTB data) [[self](https://github.com/xiaohu2015/DeepLearning_tutorials/tree/master/examples/lstm_model_ptb)] [[tutorial](https://www.tensorflow.org/versions/r0.12/tutorials/recurrent/index.html#recurrent-neural-networks)] [[paper](https://arxiv.org/pdf/1409.2329.pdf)]
 - VGG model for image classification (object recongnition) [[self](https://github.com/xiaohu2015/DeepLearning_tutorials/tree/master/examples/VGG)] [[source](https://github.com/machrisaa/tensorflow-vgg)]
 - Residual network for cifar10_dataset [[self](https://github.com/xiaohu2015/DeepLearning_tutorials/tree/master/examples/Resnet)] [[source](https://github.com/wenxinxu/resnet-in-tensorflow)] [[paper](https://arxiv.org/pdf/1603.05027v3.pdf)]
 - LSTM for time series prediction [[self](https://github.com/xiaohu2015/DeepLearning_tutorials/blob/master/examples/lstm_time_series_regression)] [[source](https://github.com/MorvanZhou/tutorials/blob/master/tensorflowTUT/tf20_RNN2.2/full_code.py)]