[MonologBundle] Add missing GroupHandler schema definitions

src/Symfony/Bundle/MonologBundle/Resources/config/schema/monolog-1.0.xsd

@@ -18,6 +18,9 @@
         <xsd:choice minOccurs="0" maxOccurs="unbounded">
             <xsd:element name="processor" type="xsd:string" />
         </xsd:choice>
+        <xsd:choice minOccurs="0" maxOccurs="unbounded">
+            <xsd:element name="member" type="xsd:string" />
+        </xsd:choice>
         <xsd:attribute name="type" type="xsd:string" use="required" />
         <xsd:attribute name="priority" type="xsd:integer" />
         <xsd:attribute name="level" type="level" />