feat: match active class docs menu on identifier

  <ul class="list-unstyled">

    {{ range .Children -}}

      {{- $active := or ($currentPage.IsMenuCurrent "docs" .) ($currentPage.HasMenuCurrent "docs" .) -}}

      {{- $active = or $active (eq .Name $currentPage.Title) -}}

      {{- $active = or $active (eq $currentPage.Section .Identifier) -}}

      <li><a class="docs-link{{ if $active }} active{{ end }}" href="{{ .URL | absURL }}">{{ .Name }}</a></li>

    {{ end -}}

  </ul>