Replace Slack link with Discord link on homepage
Replace Slack link with Discord link on homepage

Signed-off-by: Ben Aaron Goldberg <73675debcd8a436be48ec22211dcf44fe0df0a64@benaaron.dev>

RITlug/ritlug.github.io,RITlug/ritlug.github.io,RITlug/ritlug.github.io