Update signature style for optional arguments, part 3.
diff --git a/Doc/library/decimal.rst b/Doc/library/decimal.rst
index 350413f..89acbb8 100644
--- a/Doc/library/decimal.rst
+++ b/Doc/library/decimal.rst
@@ -305,7 +305,7 @@
 ---------------
 
 
-.. class:: Decimal([value [, context]])
+.. class:: Decimal(value="0", context=None)
 
    Construct a new :class:`Decimal` object based from *value*.