add more release notes for 0.73.0
add more release notes for 0.73.0

cjcjameson/concourse,cjcjameson/concourse,concourse/concourse,concourse/concourse,cjcjameson/concourse,zachgersh/concourse,concourse/concourse,concourse/concourse,zachgersh/concourse,concourse/concourse,zachgersh/concourse