Interactivity API Docs: Add withScope description

[cbravobernal]

What?

Add withScope() function description and an example.

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Co-authored-by: c4rl0sbr4v0 <cbravobernal@git.wordpress.org>
Co-authored-by: sirreal <jonsurrell@git.wordpress.org>

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[sirreal]

Thanks! I left a few suggestions but this looks good.

[sirreal]

Suggested change

	### useScope()
	### withScope()

[sirreal]

Suggested change

	When the Interactivity API runtime execute callbacks, the scope is set automatically. However, if you call an action from a callback that is not executed by the runtime, like `setInterval()`, you need to ensure that callback sets the scope. The way of doing so is by wrapping the callback with `withScope()` function.
	When the Interactivity API runtime execute callbacks, the scope is set automatically. However, if you call an action from a callback that is not executed by the runtime, like in a `setInterval()` callback, you need to ensure that the scope is properly set. Use the `withScope()` function to ensure the scope is properly set in these cases.

[sirreal]

I'd remove some of the less relevant parts of the example:

Suggested change

	const ctx = getContext();
	if ( ctx.autoplay ) {
	setInterval(
	withScope( () => {
	actions.nextImage();
	} ),
	state.transitionsSpeed
	);
	}
	setInterval(
	withScope( () => {
	actions.nextImage();
	} ),
	3_000
	);