vagrantfile: Document tested host vs guest

Fixes kata-containers#3942
Signed-off-by: Wainer dos Santos Moschetta <[email protected]>

README.md

@@ -294,12 +294,19 @@ the [vagrant](https://www.vagrantup.com) tool to create a VM with the setup as c
 as possible to the environments where CI jobs will run the tests. Thus, allowing to
 reproduce a CI job locally.
 
-Currently it is only able to create a *Fedora 32* or *Ubuntu 20.04* VM. And your workstation
-must be capable of running VMs with:
+Your workstation must be capable of running VMs with:
  * 8GB of system memory
  * ~45GB and ~20GB of disk space for the VM images (Fedora and Ubuntu, respectively) on
    the Libvirt's storage pool
 
+Currently it is only able to create a *Fedora 32* or *Ubuntu 20.04* VM. The following table
+shows the tested combinations of host versus guest.
+
+|Host \ Guest  | fedora | ubuntu |
+| --- | --- | --- |
+| Fedora 33    |   Yes  |   Yes  |
+| Ubuntu 20.04 |   No   |   Yes  |
+
 Besides having vagrant installed in your host, it is needed the [vagrant libvirt plug-in](https://github.com/vagrant-libvirt/vagrant-libvirt) (Libvirt is the provider currently used), QEMU and `rsync` (needed to copy files between
 the host and guest).