Document the "optional" argument of distutils’ Extension class
diff --git a/Doc/distutils/apiref.rst b/Doc/distutils/apiref.rst
index 30829b8..eae9078 100644
--- a/Doc/distutils/apiref.rst
+++ b/Doc/distutils/apiref.rst
@@ -261,6 +261,11 @@
| | from the source extensions if | |
| | not provided. | |
+------------------------+--------------------------------+---------------------------+
+ | *optional* | specifies that a build failure | a boolean |
+ | | in the extension should not | |
+ | | abort the build process, but | |
+ | | simply skip the extension. | |
+ +------------------------+--------------------------------+---------------------------+
.. class:: Distribution