README.md in koma-0.2.0 vs README.md in koma-0.3.0

@@ -1,6 +1,6 @@
-# Koma [![Build Status](https://travis-ci.org/k1LoW/koma.svg?branch=master)](https://travis-ci.org/k1LoW/koma)
+# Koma [![Gem](https://img.shields.io/gem/v/koma.svg)](https://rubygems.org/gems/koma) [![Build Status](https://travis-ci.org/k1LoW/koma.svg?branch=master)](https://travis-ci.org/k1LoW/koma)
 
 Koma gather host inventory without agent.
 
 ## Installation
 
@@ -10,18 +10,50 @@
 gem 'koma'
 ```
 
 And then execute:
 
-    $ bundle
+```sh
+$ bundle
+```
 
 Or install it yourself as:
 
-    $ gem install koma
+```sh
+$ gem install koma
+```
 
 ## Usage
 
-    $ koma ssh example.com
+If you login remote server via `ssh example.com`, you can execute:
+
+```sh
+$ koma ssh example.com
+```
+
+And get stdout like [this](stdout_sample.json).
+
+## Host inventory keys
+
+```sh
+$ koma keys
+memory
+ec2
+hostname
+domain
+fqdn
+platform
+platform_version
+filesystem
+cpu
+virtualization
+kernel
+block_device
+package
+user
+group
+service
+```
 
 ## Contributing
 
 1. Fork it ( https://github.com/k1LoW/koma/fork )
 2. Create your feature branch (`git checkout -b my-new-feature`)