In the manpage output the sections get rendered as refsections, but
those only go up to level 3:
> In DocBook, RefSect3 is the lowest-level section allowed in a
> RefEntry. There is no element analogous to a Sect4.
-- https://tdg.docbook.org/tdg/4.5/refsect3
While nesting refsect3 would work output wise, the DTD schema does not
allows this, and disabling schema validation can lead to graver
issues, so rather avoid that and use a formalpara [0], a paragraph
with a title, instead, but only for the title, as the inner content
will be a simpara (simple paragraph) that cannot be nested inside a
formalpara, but the resulting rendering works out well enough.
[0]: https://tdg.docbook.org/tdg/4.5/formalpara
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
E.g., render them as h6 for the HTML output.
Level 5 headings are the +++++ ones in the full page output, in the
per-chapter outputs they are level 4 and worked fine already.
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
