release image files checksums

[Paul Goyette <paul%whooppee.com@localhost>]

Is there a reason why ``build.sh install-image'' creates and populates
the $RELEASE/{MD5,SHA512} files, yet ``build.sh iso-image'' and
``build.sh iso-image-source'' do not?

# ls -1 $RELEASE/images
MD5
NetBSD-10.99.11-amd64-bios-install.img.gz
NetBSD-10.99.11-amd64-dvd.iso
NetBSD-10.99.11-amd64-install.img.gz
NetBSD-10.99.11-amd64.iso
SHA512
# cat $RELEASE/images/MD5
MD5 (NetBSD-10.99.11-amd64-bios-install.img.gz) = 9d39052321e0ac242262a8a6561780cd
MD5 (NetBSD-10.99.11-amd64-install.img.gz) = e6700ee9002ee1ca27a95b16159c5f9d
#

+---------------------+--------------------------+----------------------+
| Paul Goyette (.sig) | PGP Key fingerprint:     | E-mail addresses:    |
| (Retired)           | 1B11 1849 721C 56C8 F63A | paul%whooppee.com@localhost    |
| Software Developer  | 6E2E 05FD 15CE 9F2D 5102 | pgoyette%netbsd.org@localhost  |
| & Network Engineer  |                          | pgoyette99%gmail.com@localhost |
+---------------------+--------------------------+----------------------+