Schema Location in PicketLink Reference Documentation

The documentation available at http://docs.jboss.org/picketlink/2/2.1.7.Final/reference/ has an old reference to the location of the schema of the config files, which is currently https://github.com/picketlink/picketlink/blob/master/modules/federation/src/main/resources/schema/config/picketlink_v2.1.xsd.