docs: update related packages sections

[stdlib-bot]

This PR

• updates the related packages section of READMEs to include links to related packages.

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
math/base/special/log1pf	$\color{red}380/393$ $\color{green}+0.00%$	$\color{red}31/35$ $\color{green}+0.00%$	$\color{green}3/3$ $\color{green}+0.00%$	$\color{red}380/393$ $\color{green}+0.00%$
stats/base/ndarray/meanwd	$\color{green}99/99$ $\color{green}+0.00%$	$\color{green}3/3$ $\color{green}+0.00%$	$\color{green}1/1$ $\color{green}+0.00%$	$\color{green}99/99$ $\color{green}+0.00%$

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