Creation of new users during CSV import

According to https://confluence.atlassian.com/display/JIRA/Importing+Data+from+CSV:
You can choose to have the importer automatically create JIRA users for any values of the Assignee or Reporter field. But in documentation this is not so clear that if you just map the fields it will do that, the user normally gets confuse when doing the import on how this is going to work. We believe that explaining in the documentation how the import will map the users will help the customers and reduce this kind of question.