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
blas/ext/base/dwxdy	$\\color{green}426/426$ $\\color{green}+0.00\\%$	$\\color{green}28/28$ $\\color{green}+0.00\\%$	$\\color{green}4/4$ $\\color{green}+0.00\\%$	$\\color{green}426/426$ $\\color{green}+0.00\\%$
blas/ext/base/swxdy	$\\color{green}426/426$ $\\color{green}+0.00\\%$	$\\color{green}28/28$ $\\color{green}+0.00\\%$	$\\color{green}4/4$ $\\color{green}+0.00\\%$	$\\color{green}426/426$ $\\color{green}+0.00\\%$
math/base/special/expf	$\\color{red}494/496$ $\\color{green}+0.00\\%$	$\\color{red}23/24$ $\\color{green}+0.00\\%$	$\\color{green}4/4$ $\\color{green}+0.00\\%$	$\\color{red}494/496$ $\\color{green}+0.00\\%$
ml/base/loss/float64/hinge-gradient	$\\color{green}206/206$ $\\color{green}+0.00\\%$	$\\color{green}14/14$ $\\color{green}+0.00\\%$	$\\color{green}2/2$ $\\color{green}+0.00\\%$	$\\color{green}206/206$ $\\color{green}+0.00\\%$
ml/base/loss/float64/squared-hinge-gradient	$\\color{green}208/208$ $\\color{green}+0.00\\%$	$\\color{green}14/14$ $\\color{green}+0.00\\%$	$\\color{green}2/2$ $\\color{green}+0.00\\%$	$\\color{green}208/208$ $\\color{green}+0.00\\%$
stats/incr/nanmrmse	$\\color{green}149/149$ $\\color{green}+0.00\\%$	$\\color{green}7/7$ $\\color{green}+0.00\\%$	$\\color{green}2/2$ $\\color{green}+0.00\\%$	$\\color{green}149/149$ $\\color{green}+0.00\\%$
stats/incr/nanmvariance	$\\color{green}152/152$ $\\color{green}+0.00\\%$	$\\color{green}10/10$ $\\color{green}+0.00\\%$	$\\color{green}2/2$ $\\color{green}+0.00\\%$	$\\color{green}152/152$ $\\color{green}+0.00\\%$
stats/incr/nanwmean	$\\color{green}135/135$ $\\color{green}+0.00\\%$	$\\color{green}8/8$ $\\color{green}+0.00\\%$	$\\color{green}2/2$ $\\color{green}+0.00\\%$	$\\color{green}135/135$ $\\color{green}+0.00\\%$

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