chore: removed duplicated content

Author: mfranzke

demo/index.html

@@ -94,9 +94,6 @@ <h1>
 			<p class="scrolling-advice">
 				The following whitespace is included as a threshold,
 				<strong>please scroll down to the very end of this demo page</strong> to
-				see these images being loaded by the polyfill on The following
-				whitespace is included as a threshold,
-				<strong>please scroll down to the very end of this demo page</strong> to
 				see these images and iframe content being loaded by the polyfill on
 				<a href="https://caniuse.com/loading-lazy-attr">unsupported browsers</a>
 				(hint: