errata: Add advisories and errata affecting 13.2R

2023-06-21 FreeBSD-SA-23:04.pam_krb5
2023-06-21 FreeBSD-SA-23:06.ipv6
2023-08-01 FreeBSD-SA-23:07.bhyve
2023-08-01 FreeBSD-SA-23:08.ssh
2023-08-01 FreeBSD-SA-23:09.pam_krb5

2023-06-21 FreeBSD-EN-23:06.loader
2023-06-21 FreeBSD-EN-23:07.mpr
2023-08-01 FreeBSD-EN-23:08.vnet