Optional ReadonlyheadingThe page heading. Plain text; pass null for no heading at all.
Optional ReadonlyparagraphsParagraphs under the heading, each an HTML string so it can carry
<code> and <strong>. It is written into the page as markup, so pass
copy you control, never anything a reader typed.
Optional ReadonlyserializedHeading over that readout.
Optional ReadonlyshowThe readout that shows the HTML a download would produce. Default true.
Copy for the header this layout puts above the editor.