Update NEWS for 1.6.2.1

Reviewed-on: http://gerrit.openafs.org/9602
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Ken Dreyer <ktdreyer@ktdreyer.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Reviewed-by: Paul Smeddle <paul.smeddle@gmail.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit 5123deebdcbf634151b236bf7ff7ac7ca099b11e)

Change-Id: I2d357e3fb385fcaa0e3da056e41ef8704007da6b
Reviewed-on: http://gerrit.openafs.org/9664
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>