title: services.AddSwaggerGen() giving error
body: <p>All I'm trying to do is add swagger to an ASP.Net Core application. I'm watching a tutorial and all I see them do is add <code>services.AddSwaggerGen();</code> under the configure services area in the Startup.cs file. Like any normal service like MVC... But I get an error:</p>
  
  <blockquote>
    <p>There is no argument given that corresponds to the required formal parameter 'setupAction'...</p>
  </blockquote>
  
  <p>I don't see anyone supplying any kind of argument to <code>services.AddSwaggerGen()</code> so does anyone know what I'm missing here?</p>
  
  <p>I've added the <code>SwashBuckler.AspNetCore</code> dependency so swagger is in the application. Just don't know why it's red and giving the above error.</p>