fix #2309: allow LVM Volume Group names starting with a digit

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

PVE/Storage/Plugin.pm

@@ -145,7 +145,7 @@ PVE::JSONSchema::register_format('pve-storage-vgname', \&parse_lvm_name);
 sub parse_lvm_name {
     my ($name, $noerr) = @_;
 
-    if ($name !~ m/^[a-z][a-z0-9\-\_\.]*[a-z0-9]$/i) {
+    if ($name !~ m/^[a-z0-9][a-z0-9\-\_\.]*[a-z0-9]$/i) {
 	return undef if $noerr;
 	die "lvm name '$name' contains illegal characters\n";
     }