refactor templates layout

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

layouts/_partials/single/main-body/links/link/page-link.html

@@ -0,0 +1,36 @@
+{{- /*
+  Displays an internal link from another Page on the site.
+
+  @params sc  Site context
+  @params ref Page ref
+  */
+-}}
+
+
+<!-- Variable assignment -->
+{{- $page := $.sc.GetPage .ref -}}
+
+
+<!-- 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 -}}
+
+{{- if ( not $page ) -}}
+  {{- errorf "No Page found for ref '%q' (%q)." .ref $.sc.Page.File.Path -}}
+{{- end -}}
+
+
+<!-- Rendering -->
+
+<li>
+  {{- $.title | $page.Page.RenderString -}}:
+  <a href="{{ $page.RelPermalink }}">
+    {{- default $page.Title $page.Params.markup_title | $page.Page.RenderString -}}
+  </a>
+</li>