Outdated QEMU microvm documentation

[Stefan Hajnoczi]

Hi,
I noticed there is documentation for the microvm machine type:
https://www.qemu.org/docs/master/system/i386/microvm.html

Someone on IRC asked how to increase the number of VIRTIO devices and
I noticed the docs appear to be outdated.

It says there is no PCI or ACPI, but I believe the pcie=on and acpi=on
options are available.

Do you have time to update the docs?

Thanks,
Stefan