<?xml version="1.0" encoding="UTF-8" ?>

<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
<channel>
   {% if page.grouptype == 'category' %}
      <title>{{ site.short_url }} - Category: {{ page.category }}</title>
   {% else %}
      <title>{{ site.short_url }}</title>
   {% endif %}
   <link>{{ site.url }}</link>
   <description>{{ site.description }}</description>
   <language>{{ site.language }}</language>
   <managingEditor> {{ site.author }}</managingEditor>
   <atom:link href="rss" rel="self" type="application/rss+xml" />
   {{content}}
</channel>
</rss>

<?xml version="1.0" encoding="UTF-8" ?>

<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
<channel>
   {% if page.grouptype == 'category' %}
      <title>{{ site.shorturl }} - Category: {{ page.category }}</title>
   {% else %}
      <title>{{ site.shorturl }}</title>
   {% endif %}
   <link>{{ site.url }}</link>
   <description>{{ site.description }}</description>
   <language>{{ site.language }}</language>
   <managingEditor> {{ site.author }}</managingEditor>
   <atom:link href="rss" rel="self" type="application/rss+xml" />
   {{content}}
</channel>
</rss>

Change short_url to shorturl; just beautification
Change short_url to shorturl; just beautification
