nextcloud-server/core/templates/untrustedDomain.php

<?php /** @var array $_ */ ?>

<div class="guest-box">
	<h2><?php p($l->t('Access through untrusted domain')); ?></h2>

	<p>
		<?php p($l->t('Please contact your administrator. If you are an administrator, edit the "trusted_domains" setting in config/config.php like the example in config.sample.php.')); ?>
	</p>
	<br />
	<p>
		<?php print_unescaped($l->t('Further information how to configure this can be found in the %1$sdocumentation%2$s.', ['<a href="' . $_['docUrl'] . '" target="blank">', '</a>'])); ?>
	</p>
</div>