don't need require 'config'

Author: inouetakuya

README.md

@@ -70,7 +70,6 @@ Add the gem to your `Gemfile` and run `bundle install` to install it.
 Then initialize `Config` manually within your configure block.
 
 ```ruby
-require 'config'
 Config.load_and_set_settings(Config.setting_files("/path/to/config_root", "your_project_environment"))
 ```