docstring fix in JSONEncoder: use_decimal defaults to True

simplejson/encoder.py

@@ -185,7 +185,7 @@
         transformed into unicode using that encoding prior to JSON-encoding.
         The default is UTF-8.
 
-        If use_decimal is true (not the default), ``decimal.Decimal`` will
+        If use_decimal is true (default: ``True``), ``decimal.Decimal`` will
         be supported directly by the encoder. For the inverse, decode JSON
         with ``parse_float=decimal.Decimal``.