doc: update release notes for ice and iavf

doc: update release notes for ice and iavf

Update release notes by adding new features for ice and iavf PMD.

Fixes: de32fa2ba27b ("net/ice: support RSS for IPv6 prefix")
Fixes: 610bc231d09b ("net/ice: support RSS for IPv4 IPv6 mix of GTP")
Fixes: a9bafa9f700c ("net/ice: support flow director GTPU outer IPv4/IPv6")
Fixes: 37e444b77814 ("net/ice: support hash for GTPU protocols")
Fixes: 54851ff3375c ("net/ice: support PPPoE RSS")

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Signed-off-by: Junfeng Guo <junfeng.guo@intel.com>
Signed-off-by: Jeff Guo <jia.guo@intel.com>