title: Chart.js: adding a custom label to each item, and displaying it with a custom tooltip
body: <p>I'm building my data items like this:</p>
  
  <pre><code>data.push({ x: moment(new Date(e.StartDate)).week(), y: e.title, label:`${e.title} ${e.type} ${e.percentage}%` });
  </code></pre>
  
  <p>How do I write a custom tooltip callback to display the label string?</p>