Update documentation urls

Author: kormoc

config.php.example

@@ -45,11 +45,11 @@ $reviewhost = array(
     'dsn'           => 'mysql:host=hostname;dbname=percona',
     'user'          => 'user',
     'password'      => 'password',
-// See http://www.percona.com/doc/percona-toolkit/2.0/pt-query-digest.html#cmdoption-pt-query-digest--review
+// See http://www.percona.com/doc/percona-toolkit/2.1/pt-query-digest.html#cmdoption-pt-query-digest--review
     'review_table'  => 'review',
 // This table is optional. You don't need it, but you lose detailed stats
 // Set to a blank string to disable
-// See http://www.percona.com/doc/percona-toolkit/2.0/pt-query-digest.html#cmdoption-pt-query-digest--review-history
+// See http://www.percona.com/doc/percona-toolkit/2.1/pt-query-digest.html#cmdoption-pt-query-digest--review-history
     'history_table' => 'review_history',
 );