Bug: Dead link to modal window article on patterns

Created by: joekrie

The Patterns page has a dead link under "Modal Windows":

The Incredible Accessible Modal Window, Version 3 https://accessibility.oit.ncsu.edu/training/aria/modal-window/version-3/

It appears that the NC State Accessibility site removed it's article on modals. If you go to Accessibility Handbook content and scroll down to "Step 5", "Modal Window" is not a link.