Consistency: Rails master -> edge Rails [ci skip]

guides/source/contributing_to_ruby_on_rails.md

@@ -40,7 +40,7 @@ Having a way to reproduce your issue will be very helpful for others to help con
 * Template for Action Pack (controllers, routing) issues: [gem](https://github.com/rails/rails/blob/master/guides/bug_report_templates/action_controller_gem.rb) / [master](https://github.com/rails/rails/blob/master/guides/bug_report_templates/action_controller_master.rb)
 * Generic template for other issues: [gem](https://github.com/rails/rails/blob/master/guides/bug_report_templates/generic_gem.rb) / [master](https://github.com/rails/rails/blob/master/guides/bug_report_templates/generic_gem.rb)
 
-These templates include the boilerplate code to set up a test case against either a released version of Rails (`*_gem.rb`) or Rails master (`*_master.rb`).
+These templates include the boilerplate code to set up a test case against either a released version of Rails (`*_gem.rb`) or edge Rails (`*_master.rb`).
 
 Simply copy the content of the appropriate template into a `.rb` file and make the necessary changes to demonstrate the issue. You can execute it by running `ruby the_file.rb` in your terminal. If all goes well, you should see your test case failing.