When booting with pci-arbiter and rumpdisk and using 1024MB of memory for
qemu, booting hangs, or seems to hang, at the end of the rumpdisk boot
messages. At least 1200MB is required, currently.
* gnu/services/virtualization.scm (<hurd-vm-configuration>)[memory-size]: Bump
to 2048.
* gnu/system/examples/bare-hurd.tmpl: Suggest using 2048 here too. Update
example `guix system image' and "qemu" command lines too.
Signed-off-by: Josselin Poiret <dev@jpoiret.xyz>