JS - Clarification on Rendering Signatures in HTML Output and Markdown Support

Hi,

I'm currently using the following code to generate HTML content while skipping certain block types:
```
const htmlContent = page.html({
skipBlockTypes: ['LAYOUT_FOOTER' as ApiBlockType, 'LAYOUT_FIGURE' as ApiBlockType],
});
```

However, I noticed that signatures are not included in the HTML output. To handle this, I found that I need to manually search for signature blocks using:

```
const signatureBlocks = page.listSignatures().map(signature => {
return signature.str(); // Placeholder like [SIGNATURE]
});
```

Alternatively, I was exploring the idea of generating a full page in Markdown for more flexibility. I was also debating on using https://github.com/mixmark-io/turndown to covert html to makrdown.

For instance, using getLinesByLayoutArea to segment the page covert each page into html and into markdown after:

```
const segmented = page.getLinesByLayoutArea(true); // Sort lines in reading order

console.log("---- HEADER:");
console.log(segmented.header.map((l) => l.text).join("\n"));
console.log("\n---- CONTENT:");
console.log(segmented.content.map((l) => l.text).join("\n"));
console.log("\n---- FOOTER:");
console.log(segmented.footer.map((l) => l.text).join("\n"));
```

While this works, rendering the signature within the HTML feels a bit cumbersome. Is there a more streamlined way to include signature blocks in the HTML? Additionally, I was wondering if there are any plans to introduce a Markdown rendering option for JavaScript in the near future. It could be helpful for those of us working with simpler, more flexible outputs.