markup decorative hr tags as decorative

[StephDriver]

<hr> has been used for visual formatting, but it is focusable and read as 'separator, dimmed' which is confusing.

update the markup so that these are not focusable and are not described by screen readers.

examples:

The almost invisible pale line under 'Research Article' is an <hr>.

[StephDriver]

from #4194

• Sample 5.1, item 7. the line under this seems to be decorative, but is read out as 'separator, dimmed'
• Sample 5.3, item 3. "separator, dimmed" the <hr> following the about and before news is read aloud, but this is decorative.

[ajrbyers]

I think we will need to assess the use of hr tags. They are legitimately separators used the breakup content so no technically “decorative”.