Add another nn preset.

src/NzbDrone.Core/Indexers/Newznab/Newznab.cs

@@ -54,6 +54,7 @@ namespace NzbDrone.Core.Indexers.Newznab
                 yield return GetDefinition("OZnzb.com", GetSettings("https://api.oznzb.com"));
                 yield return GetDefinition("PFmonkey", GetSettings("https://www.pfmonkey.com"));
                 yield return GetDefinition("Usenet Crawler", GetSettings("https://www.usenet-crawler.com"));
+                yield return GetDefinition("6box", GetSettings("http://6box.me"));
             }
         }