this is pretty much what pandoc calls bracketed spans. since we only
want to support ids and classes it doesn't seem fair to copy the name,
so we'll call them "attributed span" for now. renderers are expected to
know about *all* classes they could encounter and act appropriately, and
since there are currently no classes with any defined behavior the most
appropriate thing to do for now is to reject all classes.
since support for kbd elements was added with explicit intent in #175128
it seems like a good idea to support this in nixos-render-docs instead
of just dropping it in favor of `*F12*` etc. since it's a very rare
thing in the manual and purely presentational it makes sense to use
bracketed spans instead of a new myst role.
the html-elements.lua plugin is now somewhat misnamed, but it'll go away
very soon so we don't want to bother renaming it.
this is a lot easier than adding footnote support for just the one
instance. if a use case for footnotes appears in the future (e.g. if we
wanted to render the nixpkgs manual with nixos-render-docs as well) this
decision should be reevaluated.
nixos-render-docs supports inline anchors, but not ids for blocks. it
seems wise to reserve blocks for special cases that don't have other
syntax already, like admonitions.
pandoc drops .title classes when rendering to docbook, so these are
effectively just paragraphs anyway. without support for including them
in a table of contents the complexity of parsing them in
nixos-render-docs won't be warranted.
the examples for mkPackageOption weren't terminated, leading to pretty
odd nesting of docbook (and thus html) elements. close them properly.
also turn the (likewise unclosed) fenced div containing just an anchor
id and a class that will be silently dropped to an inline anchor while
we're here. we'd have to convert it anyway later.
markdown-it parses deflists slitghtly differently than pandoc does. in
these two cases pandoc would find a deflist item while markdown-it would
not, instead it'd find a lone colon and the rest of the text.
pandoc renders these to multiple docbook paragraphs in a single
definition for the term, not multiple *actual* definitions for the same
term. this is most likely not what is intended here, so let's use
multiple paragraphs instead.
this should be placed before the appendices, not between them. might
even have a good place in the development part, but that's a decision
for another day.
pennae