feature: Added additional Unbound chart for query cache info (#6574)

* Update unbound.inc.php

* Update unbound.inc.php

* Create unbound_cache.inc.php

* Update AUTHORS.md

* Update apps.inc.php

html/includes/graphs/application/unbound_cache.inc.php

@@ -0,0 +1,30 @@
+<?php
+
+require 'includes/graphs/common.inc.php';
+
+$i            = 0;
+$scale_min    = 0;
+$nototal      = 1;
+$unit_text    = 'Query/s';
+$rrd_filename = rrd_name($device['hostname'], array('app', 'unbound-cache', $app['app_id']));
+$array        = array(
+    'queries',
+    'hits',
+    'misses'
+);
+
+$colours      = 'mixed';
+$rrd_list     = array();
+
+if (rrdtool_check_rrd_exists($rrd_filename)) {
+    foreach ($array as $ds) {
+        $rrd_list[$i]['filename'] = $rrd_filename;
+        $rrd_list[$i]['descr']    = strtoupper($ds);
+        $rrd_list[$i]['ds']       = $ds;
+        $i++;
+    }
+} else {
+    echo "file missing: $rrd_filename";
+}
+
+require 'includes/graphs/generic_multi_line.inc.php';