Provide more accessibility guidance

[ajeanmahoney]

https://authors.ietf.org/en/diagrams should have more info on how to use the <artwork alt=""> attribute and the SVG <desc> element to provide descriptions of images to people who are visually impaired.

[JayDaley]

Can you please suggest text for this one.

[ajeanmahoney]

This issue has a dependency on #ietf-tools/xml2rfc#898: contents of the alt attribute don't actually appear in the HTML output.

As for the <desc> element, perhaps adding the following after the "See Validating your SVG..." paragraph:

In addition, please provide a detailed description of the artwork in the SVG <desc> element to assist readers who are visually impaired. For more information about this element, please see the W3C Accessibility Features of SVG.

[duerst]

@ajeanmahoney : Thanks for the text proposal. I think it would be better to say "in SVG <desc> elements", because there can be more than one.

[ajeanmahoney]

This guidance should also include good examples of well-annotated diagrams in RFCXML-conforming XML when we have some.