Membership - Confirm Ping error in documentation

Hi guys -

I grinded over this for two hours. Please confirm that in fact I found an error in the documentation.

In this PDF: https://premium.wpmudev.org/wp-content/uploads/2010/05/Membership-Docs-3101.pdf

I have been trying to ping Mailchimp on new Member signup, just like the example in the document. The document says, quote:

We will then add a ? so this field should have:
http://us2.api.mailchimp.com/1.3/?

However, after troubleshooting EVERYTHING I could think of, I removed the ? and it worked.

Please confirm this is an error in the documentation, and not a bug I should continue to be concerned about or look for. Thanks.