docs: fixed arrow function for example

README.md

@@ -98,7 +98,7 @@ This is the solution for you if you're just using `<script>` tags everywhere!
       .send({ name: 'Manny', species: 'cat' }) // sends a JSON post body
       .set('X-API-Key', 'foobar')
       .set('accept', 'json')
-      .end((err, res) => {
+      .end(function (err, res) {
         // Calling the end function will send the request
       });
   })();
@@ -246,7 +246,7 @@ Our breaking changes are mostly in rarely used functionality and from stricter e
 [MIT](LICENSE) © TJ Holowaychuk
 
 
-## 
+##
 
 [npm]: https://www.npmjs.com/