Add dwg mime types

function wc_edit_upload_types($existing_mimes = array()) {
    $existing_mimes['dwg'] = 'application/acad';
    $existing_mimes['dxf'] = 'image/x-dxf';
    $existing_mimes['dwf'] = 'drawing/x-dwf';
    return $existing_mimes;
}
add_filter('upload_mimes', 'wc_edit_upload_types');