Re-set up Atom feed (XML)

[beechnut]

We provide an XML-based Atom feed with latest posts. This came for free with a Jekyll plugin; we'll have to replicate in 11ty.

These articles should help figure out how to set this up:
https://conr.dev/posts/2022/07/rss-for-11ty/
https://www.11ty.dev/docs/plugins/rss/

Acceptance criteria

Beta Give feedback

1. Atom feed looks equivalent to production 18F Atom feed

[jasnakai]

Paired with @19mderose to look into this. Got stuff setup but the current version of the 11ty RSS plugin requires 11ty version 3.0.0 or higher. The current stable version of 11ty is 2.0.1. Going to look into using an older version of the RSS plugin to get it running.

[beechnut]

@jasnakai Can I encourage you to consider solutions that don't require a plugin? I'd suggest taking a look here and at the first blog post listed in the issue — this may be a quicker means to the same end.