issue #13 - update readme

Author: mikaelcom

README.md

@@ -93,10 +93,11 @@ Here are the methods that must be implemented and why:
 ### AbstractStructBase
 #### Description
 This class is the base class for any ```StructType``` class generated by [PackageGenerator](https://github.com/WsdlToPhp/PackageGenerator). It implements our [StructInterface](#structinterface) interface.
-It defines three methods:
+It defines four methods:
 - **__set_state($array)**: Useful when you load the string representation of an object that you stored using ```var_export```. It also allows you to ease the instanciation of an object that contains many properties which would be hard to instanciate using the ```__construct``` method. You can see ```__set_state``` as an hydratation method.
 - **_set($name, $value)**: As magic method ```__set``` but used by the ```__set_state``` method. Plus, defining ```__set``` method on used class by the classmap option for the [SoapClient](http://php.net/manual/en/class.soapclient.php) breaks the correct hydratation of your received objects.
-- **_get($name)**: As magic method ```__get```. Used by our [AbstractStructArrayBase](#abstractstructarraybase) class
+- **_get($name)**: As magic method ```__get```. Used by our [AbstractStructArrayBase](#abstractstructarraybase) class.
+- **jsonSerialize()**: by implementing the [\JsonSerializable](http://php.net/manual/en/class.jsonserializable.php) interface, it implements this method that allows to pass the object to the [json_encode](http://php.net/manual/en/function.json-encode.php) method so it will return the properties of the current object in an array.
 
 #### Usage
 ```php