Updating the README and adding a change log section
Updating the README and adding a change log section

Xodarap/health-data-standards,Xodarap/health-data-standards,okeefm/health-data-standards,projectcypress/health-data-standards,thecristen/health-data-standards,PheMA/health-data-standards,thecristen/health-data-standards,projectcypress/health-data-standards,okeefm/health-data-standards,PheMA/health-data-standards