Hugo - Iterate over section and subsections

index.html

{{ $allSections  := site.Sections }} <!-- "blog" and "docs" -->
{{ $docsSections := where $allSections "Section" "docs" }} <!-- "getting-started" and "deployment" -->
{{ $thisUrl      := .RelPermalink }} <!-- the URL of the current page -->

<h2>Docs</h2>

{{ range $docsSections }}
  <ul>
    <li>
      {{ .Title }}
      {{ range .RegularPages }}
      <ul>
        <li>
          {{ .Title }}
        </li>
      </ul>
      {{ end }}
    </li>

    {{ range .Sections }}
      <li> {{ .CurrentSection.Title }}
        <ul>
          {{ range .CurrentSection.RegularPages }}
          <li>
            {{ .Page.Title }}
          </li>
          {{ end }}
        </ul>
      </li>
    {{ end }}
  </ul>
{{ end }}