How can I separate my articles by category, like the example below?

[Def1ne]

My code:

[jmooring]

<ul>
  {{ range $term, $weightedPages := site.Taxonomies.categories }}
    <li>
      <a href="{{ .Page.RelPermalink }}">{{ .Page.LinkTitle }}</a>
      <ul>
        {{ range $weightedPages }}
          <li>
            <a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a>
          </li>
        {{ end }}
      </ul>
    </li>
  {{ end }}
</ul>

looks like