title: Exclude media-type sample from Web API help page
body: <p>I am newbie in Web API usage, and the problem I'm struggling with problem I can't find solution to.
  Common problem is, when instead of application/x-www-form-urlencoded media type sample, people get </p>
  
  <blockquote>
    <p>Failed to generate the sample for media type 'application/x-www-form-urlencoded'. Cannot use formatter 'FormUrlEncodedMediaTypeFormatterTracer' to write type 'Task'.</p>
  </blockquote>
  
  <p>Common suggestion is to specify own sample in the Config file, but I'm wondering, can I remove this media type help section?</p>
  
  <pre><code>config.SetSampleForType("", new MediaTypeHeaderValue("application/x-www-form-urlencoded"), typeof(object));
  </code></pre>
  
  <p>Gives me an empty section.</p>
  
  <p>Thanks in advance!</p>