[TwigBundle] added missing entry in the XSD schema

src/Symfony/Bundle/TwigBundle/Resources/config/schema/twig-1.0.xsd

@@ -20,6 +20,7 @@
         <xsd:attribute name="charset" type="xsd:string" />
         <xsd:attribute name="debug" type="xsd:string" />
         <xsd:attribute name="strict-variables" type="xsd:string" />
+        <xsd:attribute name="exception-controller" type="xsd:string" />
     </xsd:complexType>
 
     <xsd:complexType name="form">