title: PromptDialog.Choice does not show choices
body: <p>I'm looking for how we can show choices to user with <code>IDialog&lt;object&gt;</code> and <code>PromtDialog.Choice</code> method. But the thing is  below code sample doesn't show the choices. Very difficult to find code sample. Looking for a help. Thank you.</p>
  
  <pre><code> List&lt;string&gt; BotOptions = new List&lt;string&gt;();
                  BotOptions.Add("Find a Program");
                  BotOptions.Add("Find an Event");
                  PromptDialog.Choice(context, 
                      ChoiceSelectAsync,BotOptions,
                      "I didn't understand you. I'm cable to help you with", 
                      "Didn't get that", 
                      1, 
                      PromptStyle.None);
  </code></pre>