template.html

{namespace neos=TYPO3\Neos\ViewHelpers}
{namespace ts=TYPO3\TypoScript\ViewHelpers}
<div{attributes -> f:format.raw()}>
	{neos:contentElement.editable(property:'title', tag: 'h1')}
	<ts:render path="content" />
</div>

typoscript.txt

prototype(TYPO3.Neos:PrimaryContent).FoobarBookingEvent {
	condition = ${q(node).is('[instanceof Foobar.Booking:EventTemplate]')}
	type = 'Foobar.Booking:EventTemplate'
	@position = 'start'
}

prototype(Foobar.Booking:EventTemplate) < prototype(TYPO3.TypoScript:Template) {
	templatePath = 'resource://Foobar.Booking/Private/Templates/DocumentTypes/Event.html'
	node = ${documentNode}
	title = ${q(node).property('title')}

	content = TYPO3.Neos:ContentCollection {
		nodePath = 'main'
	}
}