function onMarkdownTransform( error, vfile ) {
		if ( error ) {
			return done( error );
		}
		// Syntax highlight the HTML code elements:
		hTransform( vfile, onHTMLTransform );
	}
Callback invoked after transforming Markdown to HTML.

@private
@param {(Error|null)} error - error object
@param {File} [vfile] - virtual file
@returns {void}