TIL. I found this while venturing north of vault 111. This is a note that randomly appears on dead settlers. Another way to get the vault 81 location on your map. Does
Fallout 4 Vault 81, Curie & Overseer's Guardian
Steam Community :: Guide :: Fallout 4: Vault Locations
Fallout 4: Get a room and make friends in Vault 81 | Stevivor
Medicine Bobblehead Location - Fallout 4 Wiki Guide - IGN