[Docs]: Add docs for customValidators

[KATT]

Is there an existing issue for this?

• I have searched the existing issues and my issue is unique
• My issue appears in the command-line and not only in the text editor

Description Overview

@JoshuaKGoldberg suggested I should post an issue here 🙃

• customValidators are largely undocumented
  https://github.com/search?q=repo%3Ajsx-eslint%2Feslint-plugin-react+customValidators+language%3AMarkdown&type=code&l=Markdown
• It's mentioned in the docs here and in other places, but I can't figure out how to use it

Expected Behavior

A code example on how to use customVAlidators

eslint-plugin-react version

n/a

eslint version

n/a

node version

n/a

[ljharb]

Looks like it was added in docs here, and to the rule in #160.

[danreeves]

While working on #3826 I came to the conclusion that this option never existed for the no-unstable-component-prop-pattern and was added to the documentation as a mistake: #3826 (comment)

I suggest re-labelling this issue as a bug, the fix being removing the incorrect documentation.

The original request in the linked tweet should be resolved by my PR.

The customValidators option for the prop-types/no-unused-prop-types rules is under-documented but I wouldn't consider fixing that a priority because prop-types are deprecated and removed in React 19

[ljharb]

It's still a priority, and React 19 isn't even out yet.

I think the best approach is to actually implement the option.

[danreeves]

That's fair. Improving the docs for where the option exists is doable.

I think it's not really clear what the option would do for no-unstable-component-prop-pattern. customValidators in prop-types/no-unused-prop-types is for specifying alternative validator objects to PropTypes. That doesn't really apply here. I suppose it could be used for the feature in my PR but the two different meanings could be confusing.

[ljharb]

hm, yeah that’s also true.

I’m not sure if there’s a way to update the tooling to keep the option undocumented (cc @bmish)