Some repos have ACLs with groups that contain the stable-maint-core
group, while others do not include the group at all. All governed repos
should include this team, even if they don't assert
stable:follows-policy so stable branch issues can be resolved as needed.
To make it consistent and clear, this adds stable-maint-core directly to
the ACLs for all repos under governance.
Change-Id: Ifdc429e2c9609475584f0473828d41d3f1067c72
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>