Use HTTPS

Currently, the website can only be served under HTTP and not HTTPS when accessed as the subdomain: `roadmap.rootandrebound.org`

Github pages will not serve the custom CNAME with HTTPS. If we switch the root DNS provider to Cloudflare, we could add HTTPS.

Without HTTPS, users will see "Not Secure" every time they use the search or access the website in an incognito window.
