Kitchen sink -- block quotes

[jarrodmillman]

I am not sure what needs to be done.

We probably want most of this:
https://pydata-sphinx-theme.readthedocs.io/en/stable/examples/kitchen-sink/blocks.html

We have this:
https://theme.scientific-python.org/examples/kitchen-sink/blocks/

And we also have:

• https://github.com/numpy/numpy.org/blob/main/layouts/shortcodes/blockquote.html
• numpy/numpy.org@8cfbd37

We should move the numpy stuff to the theme and use the PST styling for it. Then update numpy.org after we update the theme.