Pekka Paalanen authored Oct 20, 2021 and Pekka Paalanen committed Nov 10, 2021

For images, it's nice to have also the sources in case someone needs to
edit the image later.

For math, these hints should help typesetting math with less pain.

Thanks to @mstoeckl for the KaTeX demo link.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>