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/beta/median	$\\color{green}196/196$ $\\color{green}+100.00\\%$	$\\color{green}10/10$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}196/196$ $\\color{green}+100.00\\%$
stats/base/dists/chi/quantile	$\\color{green}274/274$ $\\color{green}+100.00\\%$	$\\color{green}8/8$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}274/274$ $\\color{green}+100.00\\%$
stats/base/dists/chisquare/quantile	$\\color{green}256/256$ $\\color{green}+100.00\\%$	$\\color{green}7/7$ $\\color{green}+100.00\\%$	$\\color{green}3/3$ $\\color{green}+100.00\\%$	$\\color{green}256/256$ $\\color{green}+100.00\\%$
stats/base/dists/f/quantile	$\\color{green}311/311$ $\\color{green}+100.00\\%$	$\\color{green}24/24$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}311/311$ $\\color{green}+100.00\\%$
stats/base/dists/gamma/quantile	$\\color{green}314/314$ $\\color{green}+100.00\\%$	$\\color{green}28/28$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}314/314$ $\\color{green}+100.00\\%$
stats/base/dists/t/quantile	$\\color{green}300/300$ $\\color{green}+100.00\\%$	$\\color{green}25/25$ $\\color{green}+100.00\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{green}300/300$ $\\color{green}+100.00\\%$

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