Node.js on Azure - Adding default documents & mime types

I deployed a node.js site to Azure and everything was working great, except I noticed that markdown (.md) files we're being served up. Found another solution where I needed to add a web.config to my site to white list that extension, but now the default documents for the site (events.html) are no longer being respected.

How do you tell in the web.config for a node.js site running on azure to "add this mime type, but do everything else the same way you were doing it"?

Here's my web.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.webServer>         
    <staticContent>
      <mimeMap fileExtension=".md" mimeType="text/x-markdown" />
    </staticContent>
    <handlers>
      <add name="iisnode" path="app.js" verb="*" modules="iisnode"/>
    </handlers>
    <rewrite>
      <rules>
        <rule name="DynamicContent">
          <conditions>
            <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="True"/>
          </conditions>
          <action type="Rewrite" url="app.js"/>
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>