Update all WCAG URLs to the equivalent 2.2 location

[lb-]

• Update all URLs that were to 2.1 to their 2.2 equivalent, I have also manually checked each URLs for any 404s
• Fixes Update all documentation links to WCAG 2.2 equivalent #1015
• Ensure all URLs are consistent (without trailing HTML) as this is the canonical URL

[lb-]

As per https://www.w3.org/WAI/standards-guidelines/wcag/new-in-22/#changes-from-wcag-21-to-wcag-22

WCAG 2.2 provides 9 additional success criteria since WCAG 2.1. They are introduced on this page.

The 2.0 and 2.1 success criteria are essentially the same in 2.2, with one exception: 4.1.1 Parsing is obsolete and removed from WCAG 2.2. More information is in WCAG 2 FAQ, 4.1.1 Parsing. WCAG 2.2 includes Notes about different languages; more information is in WCAG 2 FAQ, internationalization.

I have left the link in that this project has for 4.1.1. but it may be better to review this link in the future. As for any other differences, there are only additions with new requirements and no significant changes to existing requirements.

I have noticed that some links have better linked examples and explanations but the actual success criteria itself remains the same.

[ljharb]

I'm fine converting the 2.1 links to 2.2 as long as it doesn't imply that we're not validating parsing, since I suspect some of our rules do indeed do that.

[lb-]

OK @ljharb would you like me to further refine this PR with additional context where the links exist? Or are you happy with it in its current state?