completion of the example of multiple entinty with mappings

Author: carlossg00

book/doctrine/orm/configuration.rst

@@ -167,8 +167,11 @@ The following configuration code shows how to define two EntityManagers:
  entity_managers:
  default:
  connection: default
+ mappings: MyBundle1: ~
+ mappings: MyBundle2: ~
  customer:
  connection: customer
+ mappings: MyBundle3: ~
 
 Just like the DBAL, if you have configured multiple ``EntityManager``
 instances and want to get a specific one you can use the full service name to