[Doc] Add two papers to awesome paper list (#2936)

* PPIDataset

* Revert "PPIDataset"

This reverts commit 264bd0c960cfa698a7bb946dad132bf52c2d0c8a.

* data pipeline user guide

* remove chapter numbers

* Update data.rst

* image in dataset userguide

* update links using ref

* modify the link of save_graphs and load_graphs in dataset user guide

* move image to s3 server.

* fix links and ref

* Hide implementations that may cause confusions to the user

* add papers

* fix number of classes in Amazon Cobuy datasets

* add two papers to Awesome paper list

* Update README.md

* add four papers

* add two papers

* Add awesome papers

* Fix index in paper list
Co-authored-by: Minjie Wang <wmjlyjemaine@gmail.com>

README.md

@@ -325,6 +325,10 @@ We are currently in Beta stage.  More features and improvements are coming.
 
 1. [**GIPA: General Information Propagation Algorithm for Graph Learning**](https://arxiv.org/abs/2105.06035), *Qinkai Zheng, Houyi Li, Peng Zhang, Zhixiong Yang, Guowei Zhang, Xintan Zeng, Yongchao Liu*
 
+1. [**Graph Ensemble Learning over Multiple Dependency Trees for Aspect-level Sentiment Classification**](https://arxiv.org/abs/2103.11794), NAACL'21, *Xiaochen Hou, Peng Qi, Guangtao Wang, Rex Ying, Jing Huang, Xiaodong He, Bowen Zhou*
+
+1. [**Enhancing Scientific Papers Summarization with Citation Graph**](https://arxiv.org/abs/2104.03057), AAAI'21, *Chenxin An, Ming Zhong, Yiran Chen, Danqing Wang, Xipeng Qiu, Xuanjing Huang*
+
 </details>
 
 ## Installation