[Bug] unpkg links for Rule sets page

[philljenkins]

Describe the bug

1. Links on the toolkit's Checker rule sets page are returning a error message:

• Internal Server Error

and the url looks down level/odd

• https://unpkg.com/[email protected]/help/...

2. Checker rule sets page is failing to load in Firefox

To Reproduce
Steps to reproduce the behavior:

1. Go to Checker rule sets page
2. Click on any link
3. See error

Expected behavior

• Links should be updated with latest release number
• Archived releases should also work

Some example links:

• https://unpkg.com/accessibility-checker-engine@next/help/en-US/img_alt_redundant.html...
• https://unpkg.com/[email protected]/help/en-US/img_alt_redundant.html...
• https://unpkg.com/[email protected]/help/en-US/img_alt_redundant.html...

Browser & platform: fails on the following

• OS: macOS, Browser: Chrome & Firefox
• OS: Android, Browser: Chrome

Definition of Done

• [ ] Design artifacts reviewed
• Work item implemented
• Automated test case created (when applicable)
• Unit test completed
• Run Checker (when applicable)
• Manual and Screen Reader Testing (when applicable)
• Video recording of user experience walkthrough (if impact to UX)
• PR created

[philljenkins]

• The 4.0.3 link that was working last night is now down also. Looks like this started a week ago and is spreading:
  A lot of packages have Internal Server Error unpkg/unpkg#440
• @tombrunet thinks the problem is at least isolated to the help. He thinks for the tools to fetch the engine, we use jsdelivr

[philljenkins]

The extension help appears to be unaffected because the Checker's Help is pointing to our own servers for that. So, at least the major workflows appear to be unaffected for now. We'll have to keep an eye on it, but, I don't think it's a drop everything item at the moment and hopefully should fix itself soon.

[philljenkins]

Help files are correctly displaying
from this Toolkit page

• https://www.ibm.com/able/requirements/checker-rule-sets/

such as a link to help

• https://unpkg.com/[email protected]/help/en-US/...