Block Editor: Fix typo in URLInput's onKeyDown prop documentation

[chiilog]

What?

This pull request updates the URLInput component to correctly handle keyboard events. The prop onKeydown is changed to onKeyDown to ensure that keyboard events are captured as intended.

Why?

While using the URLInput component, I noticed that the onKeydown function was not triggered upon key presses. After investigating, I found that the correct React prop should be onKeyDown. This change is necessary for the component to respond to keyboard events.

not work

<URLInput
	value={ link || '' }
	onChange={ ( value ) =>
		onSetLinkHandler( value )
	}
	onKeydown={ (
		event: KeyboardEvent
	) => {
		console.log( event );
	} }
/>

work

<URLInput
	value={ link || '' }
	onChange={ ( value ) =>
		onSetLinkHandler( value )
	}
-	onKeydown={ (
+	onKeyDown={ (
		event: KeyboardEvent
	) => {
		console.log( event );
	} }
/>

How?

The change is a simple update in the component's props, replacing onKeydown with onKeyDown. This aligns with the standard React event naming conventions and ensures that the component's event handling functions as expected.

Testing Instructions

1. Open a post or page within the Gutenberg editor.
2. Insert a block that utilizes the URLInput component.
3. Try using the keyboard with the URLInput component and observe if the onKeyDown event is fired (you can check this using console logs or any other debugging method).
4. Ensure no other functionalities are impacted by this change.

Testing Instructions for Keyboard

To test using only the keyboard:

1. Focus on the URLInput component using the Tab key.
2. Press various keys to see if the onKeyDown event captures them (as indicated by console logs or other means).

Screenshots or screencast

[DAreRodz]

Indeed, properties should be documented in the correct case. Thanks for the fix, @chiilog. 😊