Remove things specific to the old Macintosh, and spell "Mac OS X" consistently.
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 871cec7..1117550 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -582,8 +582,8 @@
    ================ ===========================
    Windows          ``'win32'``
    Windows/Cygwin   ``'cygwin'``
-   MacOS X          ``'darwin'``
-   MacOS 9          ``'mac'``
+   Mac OS X         ``'darwin'``
+   Mac OS 9         ``'mac'``
    OS/2             ``'os2'``
    OS/2 EMX         ``'os2emx'``
    RiscOS           ``'riscos'``