Update about F22 extras backgrounds

[Luya Tshimbalanga]

New version of f22-backgrounds package including the supplemental
backgrounds is coming thanks for the help from nonamedotc, an active
Fedora proven packager happening to be a Fedora Forum administrator.

I updated the comment on the ticket to reflect the change [1].

[1] https://fedorahosted.org/design-team/ticket/394#comment:5