docs: Mention pnp_wait.exe and refine pvvxsvc.exe documentation

Virt-v2v can use pnp_wait.exe to wait for new Windows devices to
activate.  However this was not mentioned in the existing
documentation.

Also refine the documentation for pvvxsvc.exe (used only by SUSE
hosts) so that we don't mention the non-existent --firstboot* options.
This was incorrect documentation copied from virt-customize.  Just say
that it's an alternative to RHSrvAny.

Reported-by: Ming Xie
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2059287#c6
Fixes: commit ee78c06 ("customize: add support for pvvxsvc")
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

docs/virt-v2v.pod

@@ -1552,11 +1552,19 @@ script in the guest during conversion of Windows guests.
 
 See also: C<https://github.com/rwmjones/rhsrvany>
 
+=item F<pnp_wait.exe>
+
+(Recommended when doing conversions of Windows guests)
+
+This tool waits for newly installed Windows devices to become
+available before trying to configure them, for example to set network
+configuration.  It is part of the RHSrvAny project.
+
 =item F<pvvxsvc.exe>
 
-This is a Windows binary shipped with SUSE VMDP, used to install a "firstboot"
-script in Windows guests.  It is required if you intend to use the
-I<--firstboot> or I<--firstboot-command> options with Windows guests.
+This is a Windows binary shipped with SUSE VMDP, used to install a
+"firstboot" script in Windows guests.  It is an alternative to
+RHSrvAny.
 
 =back