Add RSS subscribe link to publications page

Also only show it on the English version, since we don't have
non-English RSS feeds.

Author: jnewbery

_layouts/blog.md

@@ -38,5 +38,6 @@ layout: default
   {%- endfor -%}
 </ul>
 
-<p class="rss-subscribe">subscribe <a href="{{ "/feed.xml" | relative_url }}">via RSS</a></p>
-
+{%- if page.lang == "en" -%}
+  <p class="rss-subscribe">subscribe <a href="{{ "/feed.xml" | relative_url }}">via RSS</a></p>
+{%- endif -%}

_layouts/publications.md

@@ -38,3 +38,6 @@ layout: default
   {%- endfor -%}
 </ul>
 
+{%- if page.lang == "en" -%}
+  <p class="rss-subscribe">subscribe <a href="{{ "/feed.xml" | relative_url }}">via RSS</a></p>
+{%- endif -%}