Update 1.16.0 release date Add 1.16.0-rc2. release date
Update 1.16.0 release date
Add 1.16.0-rc2. release date

Signed-off-by: Lachlan Evenson <d71daa65b1c23a15f538ae9429ab51eec6ef95f0@microsoft.com>

kubernetes/sig-release