[3.10] bpo-30677: [doc] mention that os.mkdir() can raise FileNotFoundError (GH-31548) (GH-31877)



(cherry picked from commit 879fbd9472753149b627f32add3ddca90ac47ab7)


Co-authored-by: slateny <46876382+slateny@users.noreply.github.com>

Automerge-Triggered-By: GH:iritkatriel
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 5b2c2e0..2a1ea05 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -2041,7 +2041,8 @@
 
    Create a directory named *path* with numeric mode *mode*.
 
-   If the directory already exists, :exc:`FileExistsError` is raised.
+   If the directory already exists, :exc:`FileExistsError` is raised. If a parent
+   directory in the path does not exist, :exc:`FileNotFoundError` is raised.
 
    .. _mkdir_modebits: