add class KerberosApacheAuth and example code

example-apache-kerberos.php

@@ -0,0 +1,19 @@
+<?php
+
+require('vendor/autoload.php');
+
+// dfs paths not working
+$host = 'dc.domain.local';
+$share = 'netlogon';
+
+$auth = new \Icewind\SMB\KerberosApacheAuth();
+$serverFactory = new \Icewind\SMB\ServerFactory();
+
+$server = $serverFactory->createServer($host, $auth);
+
+$share = $server->getShare($share);
+
+$files = $share->dir('/');
+foreach ($files as $file) {
+	echo $file->getName() . "\n";
+}