refactor templates layout

@see https://gohugo.io/templates/new-templatesystem-overview/

layouts/partials/single/main-body/comments.html

@@ -1,33 +0,0 @@
-{{- /*
-  Displays comments for an item
-
-  @params pc  Page context
-  @params sc  Site context
-  */
--}}
-
-
-<!-- Validation -->
-
-{{- if ( not ( isset . "sc" ) ) -}}
-  {{- errorf "No site context received" -}}
-{{- end -}}
-
-{{- if ( not ( isset . "pc" ) ) -}}
-  {{- errorf "No page context received (%q)" .sc.Page.File.Dir -}}
-{{- end -}}
-
-
-<!-- Rendering -->
-
-<section class="site-content__comments">
-  <h2
-    class="subheading subheading--comments"
-    id="comments"
-  >
-    Comments
-  </h2>
-  <ul class="comment__thread">
-    {{ .pc.RenderShortcodes }}
-  </ul>
-</section>