hugo-whisper-theme/layouts/partials/sidebar.html

{{$currentNode := .}}
<div class="docs-menu">
  <h4>{{ .Section | humanize }}</h4>
  <ul>
    {{ range (where .Site.RegularPages "Section" .Section) sort .Site.RegularPages ".Weight" }}
    <li class="{{ if eq .File.UniqueID $currentNode.File.UniqueID }}active {{ end }}">
      <a href="{{ .Permalink }}">{{ .Title }}</a>
    </li>
    {{ end }}
  </ul>
</div>