`npm run update-reference` is outdated

[howard-e]

Given that the repository structure of https://github.com/w3c/aria-practices has changed and http://w3c.github.io/aria-practices has now been stubbed to point to the new APG website, the cloned APG repository's paths and website references in scripts/update-reference.js needs to be updated to import the examples correctly.

The error when running npm run update-reference <example>:

Cloning the aria-practice repo.
Locating the matching example file /path/to/aria-at/scripts/tmp/examples/alert/alert.html.
The example html '/path/to/aria-at/scripts/tmp/examples/alert/alert.html' does not exist. Please enure the current example html utl is in the references.csv file.