added missing lang string vm_id_txt to en + de language files

interface/web/vm/lib/lang/de_openvz_ip_list.lng

 <?php
 $wb['list_head_txt'] = 'OpenVZ IP-Adressen';
 $wb['server_id_txt'] = 'Server';
+$wb['vm_id_txt'] = 'VM';
 $wb['ip_address_txt'] = 'IP-Adresse';
 $wb['reserved_txt'] = 'Reserviert';
 ?>

interface/web/vm/lib/lang/en_openvz_ip_list.lng

 <?php
 $wb["list_head_txt"] = 'OpenVZ IP addresses';
 $wb["server_id_txt"] = 'Server';
+$wb['vm_id_txt'] = 'VM';
 $wb["ip_address_txt"] = 'IP address';
 $wb["reserved_txt"] = 'Reserved';
 ?>
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