title: How to mention a user/group in a new message to a channel?
body: <p>I checked the samples/API references here:</p>
  
  <ul>
  <li><a href="https://msdn.microsoft.com/en-us/microsoft-teams/connectors" rel="noreferrer">https://msdn.microsoft.com/en-us/microsoft-teams/connectors</a></li>
  <li><a href="https://dev.outlook.com/Connectors/GetStarted" rel="noreferrer">https://dev.outlook.com/Connectors/GetStarted</a></li>
  <li><a href="https://dev.outlook.com/Connectors/Reference" rel="noreferrer">https://dev.outlook.com/Connectors/Reference</a></li>
  </ul>
  
  <p>But cannot find how to mention someone in a new message to a channel.</p>