title: Golang: How to sort slices by days of the week?
body: <p>I have a slice of strings which contains the days of the week like this:</p>
  
  <pre><code>days := []string{"M", "Th", "W", "F", "T", "S", "Su"}
  </code></pre>
  
  <p>How do I sort them so it will output like this:</p>
  
  <pre><code>[M T W Th F S Su]
  </code></pre>
  
  <p>starting with Monday.</p>