docs: update Markdown equation elements

[stdlib-bot]

This PR

• updates equation elements found in Markdown files

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/anglit/cdf	$\\color{green}327/327$ $\\color{green}+100.00\\%$	$\\color{green}27/27$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}327/327$ $\\color{green}+100.00\\%$
stats/base/dists/anglit/entropy	$\\color{green}194/194$ $\\color{green}+100.00\\%$	$\\color{green}9/9$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}194/194$ $\\color{green}+100.00\\%$
stats/base/dists/anglit/pdf	$\\color{green}319/319$ $\\color{green}+100.00\\%$	$\\color{green}25/25$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}319/319$ $\\color{green}+100.00\\%$
stats/base/dists/anglit/skewness	$\\color{green}175/175$ $\\color{green}+100.00\\%$	$\\color{green}9/9$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}175/175$ $\\color{green}+100.00\\%$
stats/base/dists/truncated-normal/pdf	$\\color{red}295/330$ $\\color{green}+89.39\\%$	$\\color{green}15/15$ $\\color{green}+100.00\\%$	$\\color{red}2/3$ $\\color{green}+66.67\\%$	$\\color{red}295/330$ $\\color{green}+89.39\\%$

The above coverage report was generated for the changes in this PR.