BbPress add subforum description

function xx_list_forums( $args = '' ) {

    // Define used variables
    $output = $sub_forums = $topic_count = $reply_count = $counts = '';
    $i = 0;
    $count = array();

    // Parse arguments against default values
    $r = bbp_parse_args( $args, array(
        'before'            => '<ul class="bbp-forums-list">',
        'after'             => '</ul>',
        'link_before'       => '<li class="bbp-forum">',
        'link_after'        => '</li>',
        'count_before'      => ' (',
        'count_after'       => ')',
        'count_sep'         => ', ',
        'separator'         => ', ',
        'forum_id'          => '',
        'show_topic_count'  => true,
        'show_reply_count'  => true,
    ), 'list_forums' );

    // Loop through forums and create a list
    $sub_forums = bbp_forum_get_subforums( $r['forum_id'] );
    if ( !empty( $sub_forums ) ) {

        // Total count (for separator)
        $total_subs = count( $sub_forums );
        foreach ( $sub_forums as $sub_forum ) {
            $i++; // Separator count

            // Get forum details
            $count     = array();
            $show_sep  = $total_subs > $i ? $r['separator'] : '';
            $permalink = bbp_get_forum_permalink( $sub_forum->ID );
            $title     = bbp_get_forum_title( $sub_forum->ID );
            $content   = bbp_get_forum_content($sub_forum->ID) ;

            // Show topic count
            if ( !empty( $r['show_topic_count'] ) && !bbp_is_forum_category( $sub_forum->ID ) ) {
                $count['topic'] = bbp_get_forum_topic_count( $sub_forum->ID );
            }

            // Show reply count
            if ( !empty( $r['show_reply_count'] ) && !bbp_is_forum_category( $sub_forum->ID ) ) {
                $count['reply'] = bbp_get_forum_reply_count( $sub_forum->ID );
            }

            // Counts to show
            if ( !empty( $count ) ) {
                $counts = $r['count_before'] . implode( $r['count_sep'], $count ) . $r['count_after'];
            }

            // Build this sub forums link
            $output .= $r['link_before'] . '<a href="' . esc_url( $permalink ) . '" class="bbp-forum-link">' .
                       $title . $counts . '</a>' .
                       $show_sep . $r['link_after'] .
                       '<div class="bbp-forum-content">'.$content.'</div>';
        }

        // Output the list
        echo $r['before'] . $output . $r['after'];
    }
}
add_filter( 'bbp_list_forums', 'xx_list_forums' );