add mysql authentification command to chapter 2.Running the Test Suite

guides/source/contributing_to_ruby_on_rails.textile

@@ -184,6 +184,10 @@ We need first to delete +.bundle/config+ because Bundler remembers in that file
 
 In order to be able to run the test suite against MySQL you need to create a user named +rails+ with privileges on the test databases:
 
+<shell>
+mysql -u root mysql -p
+</shell>
+
 <shell>
 mysql> GRANT ALL PRIVILEGES ON activerecord_unittest.*
        to 'rails'@'localhost';