title: 'Task' does not contain a definition for 'CompletedTask' for C#
body: <p>I'm following the tutorial at <a href="https://discord.foxbot.me/docs/guides/getting_started/intro.html" rel="noreferrer">https://discord.foxbot.me/docs/guides/getting_started/intro.html</a> to a tee, and yet I'm getting an error when I try to use</p>
  
  <pre><code>return Task.CompletedTask
  </code></pre>
  
  <p>and I get this error</p>
  
  <pre><code>'Task' does not contain a definition for 'CompletedTask'
  </code></pre>
  
  <p>I am</p>
  
  <pre><code>using System.Threading.Tasks
  </code></pre>