Tech currently has a policy that TiCs should add billing-related notes to the comments of each event. However, this is often forgotten after an event.

Tracker should send an email some time after an event completes that reminds TiCs to do so, potentially conditional on whether they've commented since the event ended.

Wellington also noted that we could send Slack notifications. It looks like Tracker is a bot, so we could roughly associate Tracker users and Slack users by email/phone. I'm not sure if that should be broken out into another issue.