LaTeX math mode tweaks for MathJax

[nhejazi]

Based on https://bookdown.org/yihui/blogdown/output-format.html, note that the use of LaTeX's math mode in blog posts requires the addition of backticks to ensure that all content is rendered correctly by MathJax. That is, a simple expression like $x + \alpha$ should instead be typeset with backticks around it. See the plain text of this post for an example.