<?= $this->form->label(t('Email domain restriction for sign up'), 'registration_email_domain') ?>
<?= $this->form->text('registration_email_domain', $values, $errors, array('placeholder="domain1.tld, domain2.tld, domain3.tld"')) ?>
<p class="form-help"><?= t('Only people with this email address will be allowed to sign up.') ?></p>

<fieldset>
    <legend><?= t('Registration') ?></legend>
    <?= $this->form->label(t('Email domain restriction for sign up'), 'registration_email_domain') ?>
    <?= $this->form->text('registration_email_domain', $values, $errors, array('placeholder="domain1.tld, domain2.tld, domain3.tld"')) ?>
    <p class="form-help"><?= t('Only people with this email address will be allowed to sign up.') ?></p>
</fieldset>

Add fieldset to config form
Add fieldset to config form
