How to add and mark an event in a chart on a Zendesk custom query?

We built a simple query based on the [default] Tickets Created By Date query. In columns we are using "ticket created - month". Our team wants to add date markers for certain product releases or notable events on top of the chart, so we can track how those events impacted volume. We've chatted with Zendesk Explore support, but they aren't sure. Any workarounds? Thanks!