Add a guide for adding a setting to an existing tools panel like typography

[fabiankaegy]

Essentially a guide for <InspectorControls group="typography"> with the usage of the experimental ToolsPanelItem

<InspectorControls group="typography">
	<ToolsPanelItem
		hasValue={() => !!value}
		label={__('Labelt', 'namespace')}
		onDeselect={() => setAttributes({ value: undefined })}
		resetAllFilter={() => ({
			value: undefined,
		})}
		onSelect={() => setAttributes({ value: 'left' })}
		panelId={clientId}
	>
		<ToggleGroupControl
			label={__('Label', 'namespace')}
			value={value}
			onChange={(value) => setAttributes({ value: value })}
		>
			<ToggleGroupControlOption value="left" label={__('Left', 'namespace')} />
			<ToggleGroupControlOption value="right" label={__('Right', 'namespace')} />
		</ToggleGroupControl>
	</ToolsPanelItem>
</InspectorControls>