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
stats/base/dists/gumbel/logpdf	$\color{green}298/298$ $\color{green}+100.00\%$	$\color{green}23/23$ $\color{green}+100.00\%$	$\color{green}4/4$ $\color{green}+100.00\%$	$\color{green}298/298$ $\color{green}+100.00\%$
stats/base/dists/pareto-type1/logpdf	$\color{green}339/339$ $\color{green}+100.00\%$	$\color{green}25/25$ $\color{green}+100.00\%$	$\color{green}4/4$ $\color{green}+100.00\%$	$\color{green}339/339$ $\color{green}+100.00\%$

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