Fragments: The schema doc example broken due to moved HelloWorldSchema example

[ynnob]

Broken Example in The schema documentation

The following example is broken since the HelloWorldSchema example #oldref has been moved to IfcImporter

engine_docs/docs/fragments/schema.md

Lines 48 to 52 in 46a733a

	<div style={{position: "relative"}}>
	<iframe src="https://thatopen.github.io/engine_fragment/examples/HelloWorldSchema/"></iframe>
	<button class="full-screen-btn" onClick={() => window.open("https://thatopen.github.io/engine_fragment/examples/HelloWorldSchema/")}> Go Full Screen</button>
	</div>