docs: cloud-hypervisor only supports stream vsock

Signed-off-by: Bouke van der Bijl <i@bou.ke>

docs: fix the description of host/guest in vsock

In Connecting from Host to Guest section, the host/guest are misused,
this patch fix that.

Signed-off-by: Yi Wang <foxywang@tencent.com>

doc: Add VSOCK doc page

Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Co-authored-by: Sebastien Boeuf <sebastien.boeuf@intel.com>