Accordion headings are not accessible to screen readers

Because the spoiler/accordion headings are given a role of button (e.g., <h2 role="button">), the heading is not recognized by screen readers. For assistive technology to identify the heading, it needs to be placed outside of the button: something like <h2><a role="button"></a></h2> or <h2><button></button></h2>. Would it be possible to make this change in the plugin? Thanks for maintaining this plugin!