Little utility to add element in .config app file
<p>I need to make a little utility that upgrade an xml .config c# application file outside that application.</p>
<p>I just need to add this element:</p>
<pre><code>&lt;?xml version=&quot;1.0&quot;?&gt;
  &lt;configuration&gt;

  ...

  ...

  &lt;startup useLegacyV2RuntimeActivationPolicy=&quot;true&quot;&gt;
    &lt;supportedRuntime version=&quot;v4.0&quot; sku=&quot;.NETFramework,Version=v4.5.2&quot;/&gt;
  &lt;/startup&gt;
&lt;/configuration&gt;
</code></pre>
<p>Which is the easy way?</p>