adding a note to the prefix owner

static/resources/template_doi_not_found.html

@@ -93,6 +93,7 @@ <h1>DOI NOT FOUND: <code class="doi-not-found">10.1109/123123123</code></h1>
 						<h2 class="title">WHAT CAN I DO NEXT?</h2>
 						<ul>
 							<li>If you believe this DOI is valid, you may <strong>report this error</strong> to the responsible DOI Registration Agency using the form below.</li>
+							<li>If your organization is the steward of this DOI prefix, please make sure you have completed registration of this DOI with your Registration Agency.</li>
 							<li>You can try to search again from <a href='#'>DOI.ORG homepage</a></li>
 						</ul>
 					</div>