v2v: document --in-place

Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>

v2v/virt-v2v.pod

@@ -15,6 +15,8 @@ virt-v2v - Convert a guest to use KVM
 
  virt-v2v -i disk disk.img -o glance
 
+ virt-v2v -ic qemu:///system qemu_guest --in-place
+
 =head1 DESCRIPTION
 
 Virt-v2v converts guests from a foreign hypervisor to run on KVM.  It
@@ -75,6 +77,9 @@ booting the guest directly in qemu (mainly for testing).
 I<-o rhev> is used to write to a RHEV-M / oVirt target.  I<-o vdsm>
 is only used when virt-v2v runs under VDSM control.
 
+I<--in-place> instructs virt-v2v to customize the guest OS in the input
+virtual machine, instead of creating a new VM in the target hypervisor.
+
 =head1 EXAMPLES
 
 =head2 Convert from VMware vCenter server to local libvirt
@@ -333,6 +338,18 @@ For I<-i disk> only, this specifies the format of the input disk
 image.  For other input methods you should specify the input
 format in the metadata.
 
+=item B<--in-place>
+
+Do not create an output virtual machine in the target hypervisor.
+Instead, adjust the guest OS in the source VM to run in the input
+hypervisor.
+
+This mode is meant for integration with other toolsets, which take the
+responsibility of converting the VM configuration, providing for
+rollback in case of errors, transforming the storage, etc.
+
+Conflicts with all I<-o *> options.
+
 =item B<--machine-readable>
 
 This option is used to make the output more machine friendly