Footnotes: Implemented HTML5 markup updates in HBS files...
- Removed container div element and moved its class/role attributes to the section element.
- Removed "wb-inv" class from h2 element (fixes gh-2707).
- Replaced letters with dashes+numbers in the IDs of multi-referenced footnotes (fixes gh-3257).
Merge pull request #4019 from EricDunsworth/v4.0-footnotes-html5-markup

Footnotes: Implemented HTML5 markup updates in HBS files...