Add RSS Feed Subscribe Button

[ninjaofawesome]

Background:
The Astoria tech meetup page is a RSS feed to find information about upcoming events without having to rely on social media. Having a button to subscribe to that makes it much nicer!

Todo:

1. create a RSS feed button component. Currently there is no design, so we could opt to use an icon instead.
2. Be sure to keep accessibility in mind when making the button. It should be findable by users using screen readers, accessible to those who rely on mouse and touch, not too small or too big, etc.
   3.For now, plop it somewhere on the page. It could be on a banner, at the top or bottom of the feed, wherever! There's no layout yet to decide where it should be.
3. Write some tests to see if the button works as intended.

[ryandotfurrer]

@ninjaofawesome I'm happy to take this on!

[ryandotfurrer]

What are you all using for testing?

I've created the component and added it to MainLayout, check it out in my personal fork if you'd like.