Filter rel next/prev link in head of paginated archive pages

filter-rel-nextprev-link-in-head-of-paginated-archive-pages.php

function sp_titles_paged_rel($html, $paged) {
	$html = '';
	if ($paged) {
		$html .= '<link rel="prev" href="' . get_pagenum_link($paged - 1) . '">';
		$html .= '<link rel="next" href="' . get_pagenum_link($paged + 1) . '">';
	}
	return $html;
}
add_filter('seopress_titles_paged_rel', 'sp_titles_paged_rel', 9, 2);