docs: kvm: convert devices/vfio.txt to ReST

- Use standard title markup;
- adjust lists;
- mark code blocks as such.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Documentation/virt/kvm/devices/index.rst

@@ -13,3 +13,4 @@ Devices
    mpic
    s390_flic
    vcpu
+   vfio

Documentation/virt/kvm/devices/vfio.txt → Documentation/virt/kvm/devices/vfio.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+===================
 VFIO virtual device
 ===================
 
 Device types supported:
-  KVM_DEV_TYPE_VFIO
+
+  - KVM_DEV_TYPE_VFIO
 
 Only one VFIO instance may be created per VM.  The created device
 tracks VFIO groups in use by the VM and features of those groups
@@ -23,14 +27,15 @@ KVM_DEV_VFIO_GROUP attributes:
 	for the VFIO group.
   KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table
 	allocated by sPAPR KVM.
-	kvm_device_attr.addr points to a struct:
+	kvm_device_attr.addr points to a struct::
 
 		struct kvm_vfio_spapr_tce {
 			__s32	groupfd;
 			__s32	tablefd;
 		};
 
-	where
-	@groupfd is a file descriptor for a VFIO group;
-	@tablefd is a file descriptor for a TCE table allocated via
+	where:
+
+	- @groupfd is a file descriptor for a VFIO group;
+	- @tablefd is a file descriptor for a TCE table allocated via
 	  KVM_CREATE_SPAPR_TCE.