doc-glossary should be allowed on section not dl

[mattgarrish]

The example for doc-glossary in the DPUB-ARIA 1.0 release shows it on a dl list, but it is defined as a landmark role as glossaries aren't exclusively marked up as definition lists by publishers. It's also defined as a landmark in the accessibility mappings.

We're updating the example for the 1.1 release to show it on a section, but we'll also need this document updated to reflect the correct usage.