Add more descriptive metadata to the ISO images.

PR: 		146079
Submitted by: 	Roman Bogorodskiy
MFC after: 	3 days
X-MFC-10.1: 	yes
Sponsored by:	The FreeBSD Foundation


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273204 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f