Update README

Add an example command on how to run tests

Author: mriddle

Readme.md

@@ -24,6 +24,14 @@ You need a local user called 'john-doe'.
     GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP,INDEX  ON *.* TO 'john-doe'@'localhost';
     FLUSH PRIVILEGES;
 
+With mysql running locally, run
+
+    BUNDLE_GEMFILE=gemfiles/rails5.2.gemfile bundle exec rake test
+
+ Or
+
+     BUNDLE_GEMFILE=gemfiles/rails5.2.gemfile ruby -Ilib:test test/test_arhp.rb --seed 19911 --verbose
+
 ## Copyright
 
 Copyright (c) 2011 Zendesk. See MIT-LICENSE for details.