{{ define "main" }}
<div class="td-content">
	<h1>{{ .Title }}</h1>
	{{ with .Params.description }}<div class="lead">{{ . | markdownify }}</div>{{ end }}
	{{ .Content }}
<div class="section-index">
    {{ $pages := (where .Site.Pages "Section" .Section).ByWeight }}
    {{ $parent := .Page }}
    {{ if $parent.Params.no_list }}
    {{/* If no_list is true we don't show a list of subpages */}}
    {{ else if $parent.Params.simple_list }}
    {{/* If simple_list is true we show a bulleted list of subpages */}}
        <ul>
            {{ range $pages }}
                {{ if eq .Parent $parent }}
                    <li><a href="{{ .Permalink }}">{{- .Title -}}</a></li>
                {{ end }}
            {{ end }}
        </ul>
    {{ else }}
    {{/* Otherwise we show a nice formatted list of subpages with page descriptions */}}
	<hr class="panel-line">
        {{ range $pages }}
            {{ if eq .Parent $parent }}
                <div class="entry">
                    <h5>
                        <a href="{{ .Permalink }}">{{- .Title -}}</a>
                    </h5>
                    <p>{{ .Description }}</p>
                </div>
            {{ end }}
        {{ end }}
    {{ end }}
</div>
	{{ if (and (not .Params.hide_feedback) (.Site.Params.ui.feedback.enable) (.Site.GoogleAnalytics)) }}
		{{ partial "feedback.html" .Site.Params.ui.feedback }}
		<br />
	{{ end }}
	{{ if (.Site.DisqusShortname) }}
		<br />
		{{ partial "disqus-comment.html" . }}
	{{ end }}
	<div class="text-muted mt-5 pt-3 border-top">{{ partial "page-meta-lastmod.html" . }}</div>
</div>
{{ end }}

{{ define "main" }}
<div class="td-content">
	<h1>{{ .Title }}</h1>
	{{ with .Params.description }}<div class="lead">{{ . | markdownify }}</div>{{ end }}
	{{ .Content }}
        {{ partial "section-index.html" . }}
	{{ if (and (not .Params.hide_feedback) (.Site.Params.ui.feedback.enable) (.Site.GoogleAnalytics)) }}
		{{ partial "feedback.html" .Site.Params.ui.feedback }}
		<br />
	{{ end }}
	{{ if (.Site.DisqusShortname) }}
		<br />
		{{ partial "disqus-comment.html" . }}
	{{ end }}
	<div class="text-muted mt-5 pt-3 border-top">{{ partial "page-meta-lastmod.html" . }}</div>
</div>
{{ end }}

Put section index in separate partial
Put section index in separate partial