Fix KVM instructions for zsh users

[bashtoni]

The instructions for downloading the KVM image fail under zsh because it tries to expand the * that is outside of the quotes.

Quoting the entire filename makes the command work on both zsh and bash.

[alexjch]

@bashtoni Thanks for your contribution. I had to modify your PR to add some configuration changes. I'm closing your PR and linking your fix with my modification for reference.