Test kramdown math -> KaTeX rendering

Processed by Jekyll into https://cben.github.io/sandbox/katex

KaTeX loaded in output via Jekyll template _layouts/katex.html.

Delimiters recognized by kramdown:

inline \(\frac{kram}{down} \sum_0^\infty\) text.

\[\frac{kram}{down} \sum_0^\infty\]

The second is display math because it occurs alone in a block.