Document or support minimum rmarkdown version

[dragonstyle]

In my testing, we appear to require markdown 2.3 or later. We should consider either documenting / checking this minimum in quarto check, or adding support for older versions, whatever makes the most sense.

[cderv]

Thanks @dragonstyle !

For reference, it seems to be an issue with extract_preserve_chunks that error when rmarkdown before 2.3 is installed.

Also for reference and context, this relates to work in #4647 adding minimum version requirement check for knitr