Hello,
phpdocx_section is included as a sample in Core/embedHTML/sample_6.php. This tag, as others from HTML Extended, works in the same way, this is using the options of the related method (addSection in this case).
MS Word allows generating sections on the same page using the continuous option. This is a simple sample (we recommend creating a single section for each embedHTML calling to simplify its use):
$html = '<p>Text</p>';
$docx->embedHTML($html, array('useHTMLExtended' => true));
$html = '
<phpdocx_section data-sectionType="continuous" data-paperType="A4" data-numberCols="3" />
<p>More text</p>
';
$docx->embedHTML($html, array('useHTMLExtended' => true));
$html = '
<phpdocx_section data-sectionType="continuous" data-paperType="A4" data-numberCols="1" />
<p>More text</p>
';
$docx->embedHTML($html, array('useHTMLExtended' => true));
Regards.