Add 0.10 release info to README.md and NEWS.md (#6471)

@nswamy wants to merge it immediately, so i'm going to do it now. I also changed the PR title.

NEWS.md

@@ -1,5 +1,14 @@
 MXNet Change Log
 ================
+## 0.10.0
+- Overhauled documentation for commonly used Python APIs, Installation instructions, Tutorials, HowTos and MXNet Architecture.  
+- Updated mxnet.io for improved readability.  
+- Pad operator now support reflection padding.  
+- Fixed a memory corruption error in threadedengine.  
+- Added CTC loss layer to contrib package. See mx.contrib.sym.ctc_loss.  
+- Added new sampling operators for several distributions (normal,uniform,gamma,exponential,negative binomial).  
+- Added documentation for experimental RNN APIs.
+
 ## 0.9.3
 - Move symbolic API to NNVM @tqchen
   - Most front-end C API are backward  compatible

README.md

@@ -22,6 +22,7 @@ deep learning systems, and interesting insights of DL systems for hackers.
 
 What's New
 ----------
+* [Version 0.10.0 Release](https://github.com/dmlc/mxnet/releases/tag/v0.10.0) - MXNet 0.10.0 Release.
 * [Version 0.9.3 Release](./docs/architecture/release_note_0_9.md) - First 0.9 official release.
 * [Version 0.9.1 Release (NNVM refactor)](./docs/architecture/release_note_0_9.md) - NNVM branch is merged into master now. An official release will be made soon.
 * [Version 0.8.0 Release](https://github.com/dmlc/mxnet/releases/tag/v0.8.0)