Add description to other layouts

- helps adding description to sub-sections,
  search, terms, archive pages

layouts/_default/list.html

@@ -7,6 +7,11 @@
 {{- if not .IsHome | and .Title }}
 <header class="page-header">
   <h1>{{ .Title }}</h1>
+  {{- if .Description }}
+  <div class="post-description">
+    {{ .Description }}
+  </div>
+  {{- end }}
 </header>
 {{- end }}