pythongh-94543: Improve tempfile.mkstemp documentation about cleanup (python#154748)

Co-authored-by: picnic-sven <88426829+picnic-sven@users.noreply.github.com>

Author: sirosen

Doc/library/tempfile.rst

@@ -257,7 +257,8 @@ The module defines the following user-callable items:
    The file descriptor is :ref:`not inherited by child processes <fd_inheritance>`.
 
    Unlike :func:`TemporaryFile`, the user of :func:`mkstemp` is responsible
-   for deleting the temporary file when done with it.
+   for closing the file descriptor (for example, using :func:`os.close`) and
+   deleting the temporary file (for example, using :func:`os.remove`).
 
    If *suffix* is not ``None``, the file name will end with that suffix,
    otherwise there will be no suffix.  :func:`mkstemp` does not put a dot