update releases.md for 2.1
update releases.md for 2.1

Signed-off-by: Abigail McCarthy <11c9e92ebda0a50403aaa14f0775524c6b133005@vmware.com>

reasonerjt/harbor,wy65701436/harbor,wy65701436/harbor,wy65701436/harbor,reasonerjt/harbor,reasonerjt/harbor,reasonerjt/harbor,reasonerjt/harbor,wy65701436/harbor,reasonerjt/harbor,wy65701436/harbor,wy65701436/harbor