add missing config option to XSD file

This option was introduced in #153.

Author: xabbuh

Resources/config/schema/monolog-1.0.xsd

@@ -71,6 +71,7 @@
         <xsd:attribute name="document-type" type="xsd:string" />
         <xsd:attribute name="ignore-error" type="xsd:string" />
         <xsd:attribute name="api_version" type="xsd:string" />
+        <xsd:attribute name="include-stacktraces" type="xsd:boolean" />
     </xsd:complexType>
 
     <xsd:simpleType name="level">