Mapping unnamed <section> element to role=generic

[jlp-craigmorten]

Follows on from https://github.com/w3c/html-aam/issues/346 (https://github.com/w3c/html-aam/pull/348).

There have been prior changes in html-aam to update the mapping of the <section> element with no accessible name to role=generic.

Filing this for consideration to make the equivalent changes to the html-aria spec for the role mapping definition of the <section> element for consistency - moving from "no corresponding role" to "generic" in the no accessible name scenario.

Pertinent areas:

• https://w3c.github.io/html-aria/#docconformance
• https://github.com/w3c/html-aria/blob/a0033adba6b35a48c8ffefef659bc4def1afa2ac/index.html#L2716
• https://www.w3.org/TR/html-aam-1.0/#html-element-role-mappings
• https://github.com/w3c/html-aam/blob/gh-pages/index.html#L2824

[jlp-craigmorten]

Re-reading the issues, may be a duplicate of https://github.com/w3c/html-aria/issues/365