title: TMLanguage, what does captures do?
body: <p>I am working on a tm language project for vscode and I'm wondering what the <code>captures</code> property on a pattern does exactly.</p>
  <p>I can't seem to figure out what the indexes of the captures object stand for and I can't find any information on it online.</p>
  <p><b>Example</b>:</p>
  <pre><code>{
      &quot;match&quot;: &quot;(group 1)(group2)&quot;
      &quot;captures&quot;: {
          &quot;0&quot;: {
               &quot;name&quot;: &quot;Name of first capture group? What does 0 mean here?&quot;
           }
      }
  }
  </code></pre>