[DOC] provide supplementary resources (dmlc#326)

* provide supplementary resources

We encourage DL beginners to check out DGL project by providing links on both English and Chinese README :)

https://github.com/diveintodeeplearning/d2l-zh/blob/master/README.md
https://github.com/diveintodeeplearning/d2l-en/blob/master/README.md

* Update README.md

README.md

@@ -145,17 +145,25 @@ For the basics of coding with DGL, please see [DGL basics](https://docs.dgl.ai/t
 
 For more realistic, end-to-end examples, please see [model tutorials](https://docs.dgl.ai/tutorials/models/index.html).
 
+
+## New to Deep Learning?
+
+Check out the open source book [*Dive into Deep Learning*](http://en.diveintodeeplearning.org/).
+
+
 ## Contributing
 
 Please let us know if you encounter a bug or have any suggestions by [filing an issue](https://github.com/dmlc/dgl/issues).
 
 We welcome all contributions from bug fixes to new features and extensions.
 We expect all contributions discussed in the issue tracker and going through PRs.  Please refer to the PR guide.
 
+
 ## The Team
 
 DGL is developed and maintained by [NYU, NYU Shanghai, AWS Shanghai AI Lab, and AWS MXNet Science Team](https://www.dgl.ai/about).
 
+
 ## License
 
 DGL uses Apache License 2.0.