Home screen call to action goes nowhere

The "Sign up for our newsletter" button doesn't go anywhere. We should contact the marketing team to find a suitable destination for this button.

In the future, the button should use some data source that isn't embedded in code, like a markdown/YAML file that the site uses to generate button text and link. Also, the home page should support the functionality to support multiple buttons (in the event that, for example, officer applications and a fall event are happening concurrently).