Discuss alternatives to `mdbook-alerts` for callout preprocessors

[mkatychev]

mdbook-alerts seems "good enough" for both the web and Github display, but IMO this is worth bringing up so that everyone can discuss

Originally posted by @vados-cosmonic in https://github.com/bytecodealliance/component-docs/pull/218#discussion_r2011271456

mdbook-admonish is one alternative to consider for this role:

Pros:

• In use by popular projects such as Tree-sitter
• Uses material design (somewhat subjective but it styling feels clearer)
• handles console outputs as their own element
• does not need workarounds to play nice with mdbook-linkcheck

Cons:

• Does not support > quote blocks https://github.com/tommilligan/mdbook-admonish/issues/72
• non zero amount of effort to move over to an alternative