RSS feed icon in IE and Firefox

Internet Explorer and Firefox (and probably other browsers as well) support an RSS feed icon being activated/displayed if a webpage offers a rss feed. The default antville.org layout already provides a link but due to a false mime-type its not recognized by Firefox or IE. Add the following link tag to your HTML headers in main page layout:
<link rel="alternate" type="application/rss+xml" title="<% site.title %>" href="<% site.url %>rss">

cf. http://en.wikipedia.org/wiki/RSS#Including_in_XHTML