[Request]: Add admonition blocks

[rlespinasse]

Is your feature request related to a problem? Please describe.

Enable us to highlight a block of text to share a note, a tip, a warning, or a caution.

Asciidoctor language markup has this kind of feature

• https://asciidoctor.org/docs/asciidoc-writers-guide/#admonitions
• https://docs.asciidoctor.org/asciidoc/latest/blocks/admonitions

Describe the solution you'd like

This is a note
<!-- .element: class="note" -->

will result in

Describe alternatives you've considered

No response

Additional context

No response