bpo-39413: os.unsetenv() is not available on Windows (GH-18108)
Update os.unsetenv() documentation: it is not available on Windows.
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 9d2e8b2..7aadbcf 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -643,7 +643,7 @@
calls to :func:`unsetenv` don't update ``os.environ``, so it is actually
preferable to delete items of ``os.environ``.
- .. availability:: most flavors of Unix, Windows.
+ .. availability:: most flavors of Unix.
.. _os-newstreams: