13.1 relnotes: Add entries for most of the "Relnotes:" notations in log

Add entries suggested by most of the "Relnotes: yes" or "maybe"
entries in the git log for releng/13.1 since the 13.0 release.

Individual sections reviewed by mm (ZFS and libarchive), bz (iwlwifi),
cperciva (EC2-related items).

Reviewed by: pauamma_gundo.com
Differential Revision: https://reviews.freebsd.org/D34881