title: How to change the value of attribute in appSettings section with Web.config transformation
body: <p>Is it possible to transform the following Web.config appSettings file:</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;appSettings&gt;
      &lt;add key="developmentModeUserId" value="00297022" /&gt;
      &lt;add key="developmentMode" value="true" /&gt;
      /* other settings here that should stay */
  &lt;/appSettings&gt;
  </code></pre>
  
  <p>into something like this:</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;appSettings&gt;
      &lt;add key="developmentMode" value="false" /&gt;
      /* other settings here that should stay */
  &lt;/appSettings&gt;
  </code></pre>
  
  <p>So, I need to remove the key <strong>developmentModeUserId</strong>, and I need to replace the value for the key <strong>developmentMode</strong>.</p>