mandevilla - minor update

Author: mikaelcom

README.md

@@ -88,7 +88,7 @@ Here are the methods that must be implemented and why:
 #### Description
 This class is the base class for any ```StructType``` class generated by [PackageGenerator](https://github.com/WsdlToPhp/PackageGenerator). It implements our [StructInteface](#structinteface) interface.
 It defines three methods:
-- **__set_state($array)**: Usefull when you load the string representation of an object that you stored using ```var_export```. It also allows you to ease the instanciation of an object that contains many properties which would be hard to instanciate using the ```__construct``` method. You can see ```__set_state``` as an hydratation method.
+- **__set_state($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