bug#37145: Qemu VM with default settings runs out of ram during guix pull

[Gregory Hablutzel]

Using recommended settings for the Qemu VM of 512 MB ram from 
https://guix.gnu.org/manual/en/html_node/Running-Guix-in-a-VM.html,
guix pull fails.
Increasing ram to 1024 MB and running on fresh VM fixes the issue.
It would probably be best to just update the command on the website to
1024 MB.
Output below.
http://termbin.com/3tp7