Merge pull request #597 from tmartin2089/master

Update README.md use case #4

README.md

@@ -310,10 +310,17 @@ The usage examples below use the unqualified names for types in the Amazon Cogni
                     'cognito-idp.<region>.amazonaws.com/<YOUR_USER_POOL_ID>' : result.getIdToken().getJwtToken()
                 }
             });
-
-            // Instantiate aws sdk service objects now that the credentials have been updated.
-            // example: var s3 = new AWS.S3();
-
+
+            //refreshes credentials using AWS.CognitoIdentity.getCredentialsForIdentity()
+            AWS.config.credentials.refresh((error) => {
+                if (error) {
+                     console.error(error);
+                } else {
+                     // Instantiate aws sdk service objects now that the credentials have been updated.
+                     // example: var s3 = new AWS.S3();
+                     console.log('Successfully logged!');
+                }
+            });
         },
 
         onFailure: function(err) {