Problem:
In h2 headings, the first tag points to an invalid anchor. This used to
work but regressed a few months ago, possibly related to
ceea6898a8.
Solution:
- Simplify the logic, don't try to be clever:
- Always use to_heading_tag() for the h2 `id`.
- Also:
- Render tags as `<span>`, because `<code>` is unnecessary and doesn't
look great in headings.
- In the main h1, use "foo.txt" as the anchor `name` (rarely used),
prefer the next found tag for the `href`.
214ce8d33c
