Modifications to September event and new onsite information page

Resolves #20 (closed)

This MR adds a Register button to the September event's jumbotron as well as a link to a new page for the event's onsite information.

Navigate to /sdv-contribution-day-sept-2022 to see the modifications to the September Event page

Navigate to /sdv-contribution-day-sept-2022/onsite-info for the new onsite information page