$this->section->addTitle($titleName, $depth); the $depth max value

[pro911]

Describe the Bug

$depth If the maximum value exceeds 3, word2007 becomes invalid

Steps to Reproduce

setp1

<?php
require __DIR__ . '/vendor/autoload.php';

$phpWord = new \PhpOffice\PhpWord\PhpWord();
$section = $phpWord->addSection();
$section->...


$this->section->addTitle('x1', 1); 
$this->section->addTitle('x2', 2); 
$this->section->addTitle('x3', 3); 
$this->section->addTitle('x4', 4); 
$this->section->addTitle('x5', 5); 

Here are the results :

Expected Behavior

I want to know what the maximum value of $depth is

Current Behavior

What is the current behavior?

Context

Please fill in your environment information:

• PHP Version: 8.1
• PHPWord Version: 1.0.0 or 0.18