This provides a plugin for callouts.
It needs to have additional CSS file added to `book.toml`,
which can be (re-)generated by `mdbook-admonish install`.
See https://github.com/tommilligan/mdbook-admonish/issues/171#issuecomment-2009166079
for more context.
Use it by adding a warning one to the architecture document.
Change-Id: I75c9a33d00acb603c6da10d3f9ce3485731c1672
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11805
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: yuka <yuka@yuka.dev>
