Add section on success criteria filtering

[mattgarrish]

Okay, new attempt. Instead of subsections for each content type and having to re-explain the limitations, I've restructured it so there is now an intro to explain once what we're trying to achieve. I then put all the guidance on identifying the content types into a separate section. And there's a final section with a table to cover the content types and what can be excluded.

The non-text content still doesn't fit with the table since it's additive. To put it in the table we'd have to re-list all the success criteria for the other content types. If we assume that CSS animations are almost never used, we can also add a few other success criteria. So, I've listed these additional SC after the table to try and make this easier to follow.

A direct link to the preview for the new section is here:
https://raw.githack.com/w3c/epub-specs/understand/sc-filter/epub34/a11y-understand/index.html#eval-filter

Edit: I also removed the script to fix the errata links from this document and the techniques because notes don't get errata.

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Preview | Diff

[sueneu]

This is making so much more sense to me now. Thank you!

Can we rename the mapping table? Since it is only for filtering success criteria, maybe if we name it something that indicates that people won't be tempted to misuse it.

Something like
"Inapplicable Success Criteria"
"When Success Criteria Can Be Skipped"

[sueneu]

Suggested change

	<h4>Content-specific success criteria</h4>
	<h4>Filtering guide</h4>

[mattgarrish]

Changing it to "Inapplicable success criteria" makes it sound like the section defines SC that never apply to EPUB. Which ones are inapplicable is a mix and match.

At one point I was using the title "Filtering table" for the section (hence the id). I'd lean to something more like that to keep it connected with the main section title. "Filtering guide" might also work.

[murata2makoto]

If the sentence "The content does not pass because the requirements have been met" still remaints, it is a bit hard to understand for non-native speakers.

Addition after seeing comments from @sueneu and @mattgarrish: Sorry about my mistake. I thought that 4.2 was also added as part of this PR.

[sueneu]

@murata2makoto
I gave this a try. Please see CR
Update accessibility reporting explanation #3024

[mattgarrish]

I believe it would be best to make a new PR for this

Yes, it confused me at first because I didn't find it in the text for this new section so I thought it was something from the closed PR. Let's not start a side discussion here.