Add RSS icon to archive pages (#1156)

If the setting “ShowRssButtonInSectionTermList” is true, I think it
makes sense to also show the RSS icon by the title in archive pages, as
we do for other article lists.

This reuses the code of `layouts/_default/list.html`.

layouts/_default/archives.html

@@ -1,7 +1,19 @@
 {{- define "main" }}
 
 <header class="page-header">
-  <h1>{{ .Title }}</h1>
+  <h1>
+        {{ .Title }}
+        {{- if and (or (eq .Kind `term`) (eq .Kind `section`)) (.Param "ShowRssButtonInSectionTermList") }}
+        <a href="index.xml" title="RSS" aria-label="RSS">
+        <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"
+            stroke-linecap="round" stroke-linejoin="round" height="23">
+            <path d="M4 11a9 9 0 0 1 9 9" />
+            <path d="M4 4a16 16 0 0 1 16 16" />
+            <circle cx="5" cy="19" r="1" />
+        </svg>
+        </a>
+        {{- end }}
+    </h1>
   {{- if .Description }}
   <div class="post-description">
     {{ .Description }}