relative links in RSS feed

[craigbox]

<description>
<![CDATA[ <p>As <a href="/news/support/announcing-1.24-eol/">previously announced</a>, support for Istio 1.24 has now officially ended.</p> <p>At this point we will no longer back-port fixes for security issues and critical bugs to 1.24. We highly recommend that you upgrade to the latest version of Istio (1.26.2) if you haven&rsquo;t already.</p> ]]>
</description>

These should be fully qualified links.

The problem is in the various rss.xml templates:

            <description>{{ `<![CDATA[` | safeHTML }}{{ $post.Content | safeHTML }}{{ `]]>` | safeHTML }}</description>

The post.Content contains relative URLs, but we want the output to be absolute.

Research kicking off points:

• https://discourse.gohugo.io/t/absolute-urls-in-rss-feeds/25971