Returns HTML for a node type description for the content type admin overview page.
$variables: An associative array containing:
function theme_node_admin_overview($variables) {
$name = $variables['name'];
$type = $variables['type'];
$output = check_plain($name);
$output .= ' <small>' . t('(Machine name: @type)', array(
'@type' => $type->type,
)) . '</small>';
$output .= '<div class="description">' . filter_xss_admin($type->description) . '</div>';
return $output;
}