title: Generate yaml swagger using Swashbuckle
body: <p>I have had no problem getting a <code>json</code> file in my Web API project using <a href="https://docs.microsoft.com/en-us/aspnet/core/tutorials/web-api-help-pages-using-swagger" rel="noreferrer">Microsoft's tutorial</a>.</p>
  
  <p>Due to some requirement I would like to be able to retrieve a <code>yaml</code> file. But the problem is there is no hook I could find to make this possible.</p>
  
  <p>Does anyone know any <strong>workaround</strong> for this problem? </p>