Update example part in docs (#304)

* Update example part in docs

* Minor fix

Author: gpengzhi

docs/examples.md

@@ -16,10 +16,16 @@ More examples are continuously added...
 * [bert](https://github.com/asyml/texar-pytorch/tree/master/examples/bert): Pre-trained BERT model for text representation
 * [gpt-2](https://github.com/asyml/texar-pytorch/tree/master/examples/gpt-2): Pre-trained OpenAI GPT-2 language model
 * [xlnet](https://github.com/asyml/texar-pytorch/tree/master/examples/xlnet): Pre-trained XLNet model for text representation
+* [vae_text](https://github.com/asyml/texar-pytorch/tree/master/examples/vae_text): VAE with a transformer decoder for improved language modeling 
+
+### Variational Autoencoder (VAE) ###
+
+* [vae_text](https://github.com/asyml/texar-pytorch/tree/master/examples/vae_text): VAE language model
 
 ### Classifier / Sequence Prediction ###  
 
 * [bert](https://github.com/asyml/texar-pytorch/tree/master/examples/bert): Pre-trained BERT model for text representation
+* [sentence_classifier](https://github.com/asyml/texar-pytorch/tree/master/examples/sentence_classifier): Basic CNN-based sentence classifier
 * [xlnet](https://github.com/asyml/texar-pytorch/tree/master/examples/xlnet): Pre-trained XLNet model for text representation
 
 ---
@@ -29,6 +35,8 @@ More examples are continuously added...
 ### Language Modeling ###
 
 * [gpt-2](https://github.com/asyml/texar-pytorch/tree/master/examples/gpt-2): Pre-trained OpenAI GPT-2 language model
+* [vae_text](https://github.com/asyml/texar-pytorch/tree/master/examples/vae_text): VAE language model
+* [xlnet](https://github.com/asyml/texar-pytorch/tree/master/examples/xlnet): Pre-trained XLNet language model
 
 ### Machine Translation ###
 
@@ -38,4 +46,5 @@ More examples are continuously added...
 ### Classification ###
 
 * [bert](https://github.com/asyml/texar-pytorch/tree/master/examples/bert): Pre-trained BERT model for text representation
+* [sentence_classifier](https://github.com/asyml/texar-pytorch/tree/master/examples/sentence_classifier): Basic CNN-based sentence classifier
 * [xlnet](https://github.com/asyml/texar-pytorch/tree/master/examples/xlnet): Pre-trained XLNet model for text representation

docs/spelling_wordlist.txt

@@ -72,3 +72,4 @@ tokenizer
 wordpiece
 unigram
 TF
+Autoencoder