Make a plan for "interactive timeline"

Blocked by: https://github.com/fecgov/fec-cms/issues/6814

This [interactive timeline](https://transition.fec.gov/pages/40th_anniversary/40th_anniversary.shtml) is linked on the [mission and history](https://www.fec.gov/about/mission-and-history/#history) page and is out of date, might need some security updates, and is a bit buggy.