Fixed docs url in function editor.

src/datasource-zabbix/metric-function-editor.directive.js

@@ -221,7 +221,8 @@ angular
             }
 
             if ($target.hasClass('fa-question-circle')) {
-              window.open("http://graphite.readthedocs.org/en/latest/functions.html#graphite.render.functions." + funcDef.name,'_blank');
+              var docSite = "http://docs.grafana-zabbix.org/reference/functions/";
+              window.open(docSite + '#' + funcDef.name.toLowerCase(),'_blank');
               return;
             }
           });