[docs] Fix Select onChange call

[siriwatknp]

Fixes #34398

Some parts of the docs did not migrate to the new arguments in #34158

• I have followed (at least) the PR section of the contributing guide.

[mui-bot]

No bundle size changes

Generated by 🚫 dangerJS against adb91d3

[oliviertassinari]

Off-topic

Why not use?

Suggested change

	onChange={(event, newValue) => setDesign(newValue)}
	onChange={(event) => setDesign(event.target.value)}

so developers can more easily switch between a native <select> (for mobile) and non-native one?

[siriwatknp]

#34158 (comment). That'd be nice, I forgot about native select. cc @michaldudak

[michaldudak]

event.target.value isn't reliable in this case. The event could be a click event on a li element that represents a select option.

[oliviertassinari]

It could be made reliable

material-ui/packages/mui-material/src/Select/SelectInput.js

Lines 285 to 295 in f2d6d61

	// Redefine target to allow name and value to be read.
	// This allows seamless integration with the most popular form libraries.
	// https://github.com/mui/material-ui/issues/13485#issuecomment-676048492
	// Clone the event to not override `target` of the original event.
	const nativeEvent = event.nativeEvent || event;
	const clonedEvent = new nativeEvent.constructor(nativeEvent.type, nativeEvent);
	Object.defineProperty(clonedEvent, 'target', {
	writable: true,
	value: { value: newValue, name },
	});

The value is of event.target.value can be: form libraries integrations.
The value of Select allowing a native select can be: using the platform where it works best.

[michaldudak]

Fair point. I'll create an issue to support event.target.value in SelectUnstyled.
As for native selects, I think it could be implemented in Material/Joy, not Base.

[siriwatknp]

@michaldudak I think it should not block this PR.

[oliviertassinari]

Very much agree, it's under the "off-topic" umbrella.