README.md in spotdog-0.1.0 vs README.md in spotdog-0.2.0

@@ -1,16 +1,22 @@
 # Spotdog
 
 [![Build Status](https://travis-ci.org/dtan4/spotdog.svg?branch=ec2-class)](https://travis-ci.org/dtan4/spotdog)
 [![Code Climate](https://codeclimate.com/github/dtan4/spotdog/badges/gpa.svg)](https://codeclimate.com/github/dtan4/spotdog)
 [![Test Coverage](https://codeclimate.com/github/dtan4/spotdog/badges/coverage.svg)](https://codeclimate.com/github/dtan4/spotdog/coverage)
+[![Dependency Status](https://gemnasium.com/dtan4/spotdog.svg)](https://gemnasium.com/dtan4/spotdog)
+[![Gem Version](https://badge.fury.io/rb/spotdog.svg)](http://badge.fury.io/rb/spotdog)
 [![MIT License](http://img.shields.io/badge/license-MIT-blue.svg?style=flat)](LICENSE)
 
 __Spotdog__ is a command line tool to send EC2 Spot Instance Pricing History to Datadog. Spotdog enables us to monitor pricing history on Datadog.
 
 (screenshot)
 
+## Supported Ruby version
+
+Ruby 2.x
+
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby
@@ -23,10 +29,22 @@
 
 Or install it yourself as:
 
     $ gem install spotdog
 
+## Prerequisites
+
+You need to set __AWS credentials__ and __Datadog API key__ as environment variables.
+
+```bash
+export AWS_ACCESS_KEY_ID=XXXXXXXXXXXXXXXXXXXX
+export AWS_SECRET_ACCESS_KEY=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+export AWS_DEFAULT_REGION=xx-yyyy-0
+
+export DATADOG_API_KEY=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+```
+
 ## Usage
 
 ```bash
 $ spotdog help
 Commands:
@@ -45,21 +63,24 @@
   i, [--instance-types=INSTANCE_TYPES]              # List of instance types
   m, [--max-results=N]                              # Number of results
   p, [--product-descriptions=PRODUCT_DESCRIPTIONS]  # List of product descriptions
   s, [--start-time=START_TIME]                      # The time which to start retriving the prices
   e, [--end-time=END_TIME]                          # The time which to stop retriving the prices
+  l, [--last-minutes=N]                             # The duration in minutes which to retrive the prices
 ```
 
 - `-i`, `--instance-type`
  - List of instance types, like `m4.large,c4.xlarge`.
 - `-m`, `--max-results`
  - Number of results
 - `-p`, `--product-descriptions`
  - List of product descriptions, like `linux_vpc,suse_vpc`. These values are allowed: `linux_vpc`, `linux_classic`, `suse_vpc`, `suse_classic`, `windows_vpc` and `windows_classic`.
 - `-s`, `--start-time`
  - The time which to start retriving the prices, like `2015-10-06 18:00 JST`
-- `-e`, `--end_time`
+- `-e`, `--end-time`
  - The time which to stop retriving the prices, like `2015-10-06 19:00 JST`
+- `-l`, `--last-minutes`
+ - The duration in minutes which to retrive the prices.
 
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. You can also run `bin/console` for an interactive prompt that will allow you to experiment.