Add RSS Feed

[MikeRogers0]

Context: https://twitter.com/blijblijblij/status/1385299506292473863

@blijblijblij suggested I add an RSS feed, which is an awesome idea. I think it should be pretty possible as this is built on top on Bridgetown, so I'm excited to add this.

[alterisian]

https://github.com/bridgetownrb/bridgetown-feed looks like a RSS feed lead for Bridgetown Rb.

[MikeRogers0]

I'm hoping to get a bit of time this weekend to work on this feature btw :)