WP Modify The Read More Link Text

// Modify The Read More Link Text
function modify_read_more_link() {
	if(get_field('readmore_text', 'options')) {
   	return '<a class="button" href="' . get_permalink() . '">' . get_field( 'readmore_text', 'options' ) . '</a>';
	} else {
   	return '<a class="button" href="' . get_permalink() . '"> ' . __( 'Readmore', 'theme_name' ) .' </a>';
	}
}

// for content more link
add_filter( 'the_content_more_link', 'modify_read_more_link' );

// for excerpt more link
add_filter( 'excerpt_more', 'modify_read_more_link' );