Add banner to old WCAG 2.0 informative documents

[alastc]

The old WCAG 2.0 informative documents are not what we want people to arrive at when looking up WCAG related things, but they are referenced so much they appear high in search engine results.

Editing them is not really possible anymore (the XML files and system are out of date), so it would be good to:

• Add a standard banner at the top of each one, pointing to the WCAG 2.2 / WCAG-latest version. Either the equivalent document, or the index.

And either:

• Create a mapping from the 2.0 documents to their WCAG 2.2 equivelent (the names changed for many SCs).
• Add a canonical URL to point to the new version in each doc

Or:

• Add a 'noindex' link for each document.

MichaelC started looking at this a while ago, but as far as I know didn't make any progress.

So the first thing is: @iadawn, can you work out how we'd update the old docs?