title: NSwag: a clear steps and clean sample on how to use class extensions in NSwag studio
body: <p>There are not clear documentation on how to extend the auto-generated TS file using NSwag. I mean the extension methods with a protector access modifier </p>
  
  <p>here a discussion with the NSwag's owner:</p>
  
  <p><a href="https://github.com/RicoSuter/NSwag/issues/1012" rel="nofollow noreferrer">https://github.com/RicoSuter/NSwag/issues/1012</a></p>
  
  <p>but there is some uncertainty among the steps followed. especially in the case when adding a static suffix and/or prefix to the controller's name.</p>
  
  <p>Can someone provide a clear explanation of how can we extend the auto-generated methods?</p>