Add custom syntax to add a downloadable file via Markdown. The possible syntax could be like the one below, similar to the image syntax.
Markdown:
?[File Name](External File Link)
Render:
<div class="convertDownloadable">
<span>Download File</span>
<a href="External File Link">File Name</a>
</div>
Added default class as per other classes in https://github.com/FAXES/markdownconvert/blob/main/dev/default.css