docs: difference between `@stdlib/regexp/whitespace` and `\s`?

### Description

The [doc of regex/whitespace](https://stdlib.io/docs/api/latest/@stdlib/regexp/whitespace) says:

> Returns a [regular expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions) to match a [white space](https://en.wikipedia.org/wiki/Whitespace_character) character.

But [\s does the same thing](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_expressions/Character_classes):

> Matches a single white space character, including space, tab, form feed, line feed, and other Unicode spaces. Equivalent to [\f\n\r\t\v\u0020\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]. For example, /\s\w*/ matches " bar" in "foo bar".

I think an explanation in the doc can be helpful. The git history of the library also doesn't shed any light on the reason. (Perhaps it was created at a time when JS was less powerful?)

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### Reproduction

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### Checklist

- [x] Read and understood the [Code of Conduct](https://github.com/stdlib-js/stdlib/blob/develop/CODE_OF_CONDUCT.md).
- [x] Searched for existing issues and pull requests.