Update 3.0.0.md (#5038)

In example, the parameter is called request but in the function it was calling req

Author: llino

3.0.0.md

@@ -13,7 +13,7 @@ In order to leverage those new nodejs features, you'll need to run at least node
 ```js
 // before
 Parse.Cloud.beforeSave('MyClassName', function(request, response) {
-  if (!passesValidation(req.object)) {
+  if (!passesValidation(request.object)) {
     response.error('Ooops something went wrong');
   } else {
     response.success();
@@ -22,7 +22,7 @@ Parse.Cloud.beforeSave('MyClassName', function(request, response) {
 
 // after
 Parse.Cloud.beforeSave('MyClassName', (request) => {
-  if (!passesValidation(req.object)) {
+  if (!passesValidation(request.object)) {
     throw 'Ooops something went wrong'; 
   }
 });