title: Add app.config file for console application in Visual studio for mac
body: <p>I referred <a href="https://stackoverflow.com/questions/46156904/how-to-use-appsettings-in-net-for-mac">this</a> to add a config file for console project. I have successfully added app.config but do not know how to use it. I cannot reference <code>System.Configuration.ConfigurationManager.AppSettings;</code></p>
  
  <p>It produces the following error,</p>
  
  <blockquote>
    <p>The typename or namespace name 'ConfigurationManager' does not exist in the 'System Configuration(' are you missong and assembly reference?)'</p>
  </blockquote>
  
  <p>I right-clicked on dependencies but cannot see the option 'add references'.</p>