Merge pull request #188 from koic/add_require_false_to_example_code_in_readme

Add `require: false` to example code in README

Author: koic

README.md

@@ -18,7 +18,7 @@ gem install rubocop-rails
 or if you use bundler put this in your `Gemfile`
 
 ```ruby
-gem 'rubocop-rails'
+gem 'rubocop-rails', require: false
 ```
 
 ## Usage