13.2R/relnotes: note 2411090f6940 for zfskeys

Note: 2411090f6940 zfskeys: Support autoloading of keys stored on ZFS

Whilst here, change the example gitref to be twelve characters long:

1234567890ab

Reviewed by: karels
Approved by: karels, re (gjb)
Differential revision: https://reviews.freebsd.org/D39172