Lấy giá trị <!-- wp:heading {"level":1} --><h1>Heading 1</h1><!-- /wp:heading --> (ok)

https://app.gitbook.com/@wordpress-lionel/s/project/lay-gia-tri-less-than-wp-heading-level-1-greater-than-less-than-h1-greater-than-heading-1-less-than