Add yml example to single table inheritance

docs/en/reference/inheritance-mapping.rst

@@ -81,30 +81,47 @@ discriminator column is used.
 
 Example:
 
-.. code-block:: php
+.. configuration-block::
 
-    <?php
-    namespace MyProject\Model;
+    .. code-block:: php
     
-    /**
-     * @Entity
-     * @InheritanceType("SINGLE_TABLE")
-     * @DiscriminatorColumn(name="discr", type="string")
-     * @DiscriminatorMap({"person" = "Person", "employee" = "Employee"})
-     */
-    class Person
-    {
-        // ...
-    }
-    
-    /**
-     * @Entity
-     */
-    class Employee extends Person
-    {
-        // ...
-    }
+        <?php
+        namespace MyProject\Model;
+        
+        /**
+         * @Entity
+         * @InheritanceType("SINGLE_TABLE")
+         * @DiscriminatorColumn(name="discr", type="string")
+         * @DiscriminatorMap({"person" = "Person", "employee" = "Employee"})
+         */
+        class Person
+        {
+            // ...
+        }
+        
+        /**
+         * @Entity
+         */
+        class Employee extends Person
+        {
+            // ...
+        }
 
+    .. code-block:: yaml
+    
+    MyProject\Model\Person:
+        type: entity
+        inheritanceType: SINGLE_TABLE
+        discriminatorColumn:
+            name: discr
+            type: string
+        discriminatorMap:
+            person: Person
+            employee: Employee
+            
+    MyProject\Model\Employee:
+        type: entity
+        
 Things to note: