Improving links from WCAG TR definitions to Understanding

[kfranqueiro]

This is a follow-up to @patrickhlauke's comment here: #1031 (comment)

Currently, any links from TR definitions (under guidelines/terms) to material under understanding must use full URLs, as the two are ultimately deployed to completely different sections of w3.org through separate processes.

This has the unfortunate effect of many links crossing versions, e.g. pointing from /TR/WCAG22 to /WAI/WCAG21/Understanding, and requires links to be far more verbose than the relative links commonly seen within source files under techniques or understanding.

Fixing 2.1 links in Eleventy build (Techniques and Understanding)

The Eleventy build process for techniques and understanding already has logic to correct the base URL on understanding links, but currently only does so within techniques pages. Applying the same logic to the Key Terms section should make this also work within term definitions.

This change can be immediately applied to update any links in 2.2 Understanding docs under Key Terms containing TR/WCAG21 to TR/WCAG22.

Supporting relative understanding paths under guidelines/terms

If we want to be able to support something like ../understanding/... within TR space, this will need:

• A one-line addition in the Eleventy build code to recognize that pattern
• More importantly, adding logic to script/wcag.js to do the equivalent link transformation on the TR end

Of course, it would also then require actually changing these links in the terms files, which I imagine would have to go through a whole process. IMO this seems like potentially a lot of effort and a bit of complexity for very little benefit; what do others think?