Adding this one line of code to your template or site wide tags will make it easier for people to subscribe to your RSS feed.
You will of course need to change the value of the title and href attributes to fit your needs. Your href should be where your full rss feed address is located (note; the feed may not be all but should be whatever was setup)
If you have multiple feeds for the url you can just specify multiple link tags.
When you enable autodiscovery for your rss feed it allows browsers and aggregators to automatically detect the RSS feed when your browsing, and it makes it easy for the user to subscribe to it.