Update release note (#609)

* update readme in ga_squad

* update readme

* fix typo

* Update README.md

* Update README.md

* Update README.md

* update readme

* update

* fix path

* update reference

* fix bug in config file

* update nni_arch_overview.png

* update

* update

* update

* add release note

* update the README.md

README.md

@@ -46,7 +46,7 @@ We encourage researchers and students leverage these projects to accelerate the
 * 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 v0.4.1 https://github.com/Microsoft/nni.git
+    git clone -b v0.5 https://github.com/Microsoft/nni.git
     cd nni	
     source install.sh	
 ```
@@ -58,7 +58,7 @@ For the system requirements of NNI, please refer to [Install NNI](docs/Installat
 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 v0.4.1 https://github.com/Microsoft/nni.git
+    git clone -b v0.5 https://github.com/Microsoft/nni.git
 ```
 * Run the mnist example.
 ```bash