Rewrite some callouts to remove most headings and reduce their content

[mdo]

Took a pass at addressing #37607 with some content edits. Tried to improve overall brevity in a lot of places while removing some headings and rewriting other parts. Also changed some callout types based on their content. /cc @patrickhlauke

Fixes #37607.

[patrickhlauke]

personally, i quite liked the headings inside the callouts ... makes it more easily skimmable (you can find what you're looking for specifically, AND it gives a hint about what the note is about and whether or not you can skip reading it altogether). so i'm a bit ambivalent here (particularly since skipping heading levels is not necessarily a WCAG failure w3c/wcag#655)

[hannahiss]

personally, i quite liked the headings inside the callouts ... makes it more easily skimmable (you can find what you're looking for specifically, AND it gives a hint about what the note is about and whether or not you can skip reading it altogether). so i'm a bit ambivalent here (particularly since skipping heading levels is not necessarily a WCAG failure w3c/wcag#655)

Yes, of course you're right, that it is not an accessibility requirement, just a good practice. However, I also find a bit strange to see callouts headings in the table of content of the page (wether they are at the good level or not), for example:

The headings HTML tags could be replaced by the use of a class like .h4 or .fw-bolder. This would also harmonize the appearance of all callouts which currently do not all have the same level of heading.

[XhmikosR]

Agreed with headings too. If a11y is an issue, we should look into using fw or hN classes maybe?

[patrickhlauke]

I also find a bit strange to see callouts headings in the table of content of the page

they do head up distinct sections of content, so personally don't think they're strange ... just a bit more specific than the very generic headings for the standard sections.

[mdo]

Going to move ahead with this one. I don't want to introduce any additional custom HTML into these for using fs-* or h* classes, and I think brevity is underrated. When we added these years ago, the intention was always short blurbs. Anything more than that should ideally be regular docs content. Open to more iterations here, but for now going to ship and iterate :).