Remove outdated pointer to optparse (fixes #11360).

The doc already points to argparse.
diff --git a/Doc/library/getopt.rst b/Doc/library/getopt.rst
index bcfc4b5..b6ab3df 100644
--- a/Doc/library/getopt.rst
+++ b/Doc/library/getopt.rst
@@ -22,9 +22,6 @@
 options similar to those supported by GNU software may be used as well via an
 optional third argument.
 
-A more convenient, flexible, and powerful alternative is the
-:mod:`optparse` module.
-
 This module provides two functions and an
 exception: