Add help page with useful subcorpora
diff --git a/data/kalamar-xl.conf b/data/kalamar-xl.conf
index 272a806..e364957 100644
--- a/data/kalamar-xl.conf
+++ b/data/kalamar-xl.conf
@@ -40,9 +40,14 @@
       mount => 'http://kalamar-export-plugin:7777',
       service => 'export-plugin-proxy'
     }],
+    navi_ext => [ {
+        "title" => "virtual_subcorpora",
+        "id" => "virtual_subcorpora"
+      }
+    ],
   },
   CSP => {
-    'frame-src' => ['self', 'https://www.youtube.com'],
+    'frame-src' => ['self', 'https://korap.ids-mannheim.de/', 'https://www.youtube.com'],
     'frame-ancestors' => ['self','http://korap.dnb.de/','https://korap.dnb.de/']
    },
  'Kalamar-Plugins' => {
@@ -51,6 +56,8 @@
   Localize => {
     dict => {
       'en_title_addon' => 'DeLiKo-XL@DNB',
+      'en_Nav_virtual_subcorpora' => 'Useful Virtual Subcorpora',
+      'de_Nav_virtual_subcorpora' => 'Nützliche virtuelle Subkorpora',
       'de_Template_intro' => 'custom/intro',
       'en_Template_intro' => 'custom/intro',
       'en_howToCite' => 'Citation Help',