Update query_builder.rst

Author: sclubricants

user_guide_src/source/database/query_builder.rst

@@ -1617,6 +1617,7 @@ Class Reference
         :rtype:     int|false
 
         Compiles and executes batch ``UPDATE`` statements.
+        The ``$constraints`` parameter takes a comma delimited string of columns, an array, an associative array, or RawSql.
 
         .. note:: When more than ``$batchSize`` field/value pairs are provided,
              multiple queries will be executed, each handling up to ``$batchSize``