docs: improve doctests for complex number typed arrays in constants

[anandkaranubc]

Progresses #4833
Resolves stdlib-js/metr-issue-tracker#521

Description

What is the purpose of this pull request?

This pull request:

• improve doctests for complex number instances in constants

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [RFC]: Improve doctests for complex number typed arrays in documentation examples (tracking issue) #4833
• [RFC]: improve doctests for complex number typed arrays in @stdlib/constants metr-issue-tracker#521

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Used a Cursor driven Skill+Workflow to achieve this migration with manual and automated sanity checks.

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
constants/complex128/nan	$\color{green}50/50$ $\color{green}+100.00%$	$\color{green}1/1$ $\color{green}+100.00%$	$\color{green}0/0$ $\color{green}+100.00%$	$\color{green}50/50$ $\color{green}+100.00%$
constants/complex128/zero	$\color{green}50/50$ $\color{green}+100.00%$	$\color{green}1/1$ $\color{green}+100.00%$	$\color{green}0/0$ $\color{green}+100.00%$	$\color{green}50/50$ $\color{green}+100.00%$
constants/complex64/nan	$\color{green}50/50$ $\color{green}+100.00%$	$\color{green}1/1$ $\color{green}+100.00%$	$\color{green}0/0$ $\color{green}+100.00%$	$\color{green}50/50$ $\color{green}+100.00%$
constants/complex64/zero	$\color{green}50/50$ $\color{green}+100.00%$	$\color{green}1/1$ $\color{green}+100.00%$	$\color{green}0/0$ $\color{green}+100.00%$	$\color{green}50/50$ $\color{green}+100.00%$

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

[anandkaranubc]

@kgryte I would still need your opinion on whether this is the right change to make. Our README files currently have slightly different code snippets than the index.js example files. This was present before too, mainly with the console.log statements being absent in the README example snippets.

Should I keep them both exactly the same as we usually do? If yes, should both follow the index.js file format?