Update custom data for apiv4 mentioning the class used for OOP coding format...

Update custom data for apiv4 mentioning the class used for OOP coding format for Multi Record Custom data sets

docs/api/v4/custom-data.md

@@ -10,12 +10,32 @@ For setting custom date fields, date format is anything understood by `strtotime
 
 ## Multi-Record Custom Data
 
-Multiple record custom data sets are treated by the API as entities, which work similarly to other entities attached to contacts (Phone, Email, Address, etc.). For example, creating a multi-record set named "Work_History" could then be accessed via the API as an entity named "Custom_Work_History". Creating a record would be done like so:
+Multiple record custom data sets are treated by the API as entities, which work similarly to other entities attached to contacts (Phone, Email, Address, etc.). For example, creating a multi-record set named "Work_History" could then be accessed via the API as an entity named "Custom_Work_History" when accessing it via all forms except for in the PHP Object Oriented format, in that format the class you will be accessing is `CustomValue`. Creating a record would be done like so:
+
+Object Oriented format:
+```php
+$results = \Civi\Api4\CustomValue::create('Test_Multi_record_custom_fields')
+  ->addValue('entity_id', 202)
+  ->addValue('Test_Field', 555)
+  ->execute();
+```
+
+Traditional:
 
 ```php
 civicrm_api4('Custom_Work_history', 'create', $params);
 ```
 
+```javascript
+CRM.api4('Custom_Test_Multi_record_custom_fields', 'create', {
+  values: {"entity_id":202, "Test_Field":555}
+}).then(function(results) {
+  // do something with results array
+}, function(failure) {
+  // handle failure
+});
+```
+
 ## Try It Out
 
 Once you have created some custom data in your system, look for it in the API explorer. Single-record data will appear as fields on the entities they extend, and multi-record data will appear in the list of entities (look under "C" alphabetically as they all start with the prefix "Custom_".