change:

This release is the first of yearly US Core updates to reflect changes to U.S. Core Data for Interoperability (USCDI) v1 and requests from the US Realm FHIR community. 

to 

This release is the yearly US Core updates to reflect changes to U.S. Core Data for Interoperability (USCDI) v2 and requests from the US Realm FHIR community. 

with this link: https://www.healthit.gov/isa/sites/isa/files/2021-07/USCDI-Version-2-July-2021-Final.pdf