Update readme (#809)

Update readme for 0.5.2

README.md

@@ -17,7 +17,7 @@
 NNI (Neural Network Intelligence) is a toolkit to help users run automated machine learning (AutoML) experiments. 
 The tool dispatches and runs trial jobs generated by tuning algorithms to search the best neural architecture and/or hyper-parameters in different environments like local machine, remote servers and cloud.
 
-### **NNI [v0.5.1](https://github.com/Microsoft/nni/releases) has been released!**
+### **NNI [v0.5.2](https://github.com/Microsoft/nni/releases) has been released!**
 <p align="center">
   <a href="#nni-v05-has-been-released"><img src="docs/img/overview.svg" /></a>
 </p>
@@ -115,7 +115,7 @@ Note:
 * We support Linux (Ubuntu 16.04 or higher), MacOS (10.14.1) in our current stage. 
 * Run the following commands in an environment that has `python >= 3.5`, `git` and `wget`.
 ```bash	
-    git clone -b v0.5.1 https://github.com/Microsoft/nni.git
+    git clone -b v0.5.2 https://github.com/Microsoft/nni.git
     cd nni	
     source install.sh	
 ```
@@ -127,7 +127,7 @@ For the system requirements of NNI, please refer to [Install NNI](docs/en_US/Ins
 The following example is an experiment built on TensorFlow. Make sure you have **TensorFlow installed** before running it.	
 * Download the examples via clone the source code.	
 ```bash	
-    git clone -b v0.5.1 https://github.com/Microsoft/nni.git
+    git clone -b v0.5.2 https://github.com/Microsoft/nni.git
 ```
 * Run the mnist example.
 ```bash

docs/en_US/Installation.md

@@ -15,7 +15,7 @@ Currently we only support installation on Linux & Mac.
 
   Prerequisite: `python >=3.5, git, wget`
   ```bash
-  git clone -b v0.5.1 https://github.com/Microsoft/nni.git
+  git clone -b v0.5.2 https://github.com/Microsoft/nni.git
   cd nni
   ./install.sh
   ```