Replaced "retreive" with "retrieve".

src/Umbraco.Web.UI.Client/docs/html/using-promises-resources.html

@@ -125,7 +125,7 @@ loadMenu: function (node) {
 
     return umbRequestHelper.resourcePromise(
         $http.get(getTreeMenuUrl(node)),
-        "Failed to retreive data for a node's menu " + node.id);
+        "Failed to retrieve data for a node's menu " + node.id);
 }</code></pre>
 <p>HTTP error handling is performed automatically inside of the <code>umbRequestHelper.resourcePromise</code> and inside of Umbraco&#39;s response interceptors.</p>
 <h2>Consuming Umbraco resources</h2>