gh-148337: Document importlib.resources security model (#148340)

Author: StanFromIreland

Doc/library/importlib.resources.rst

@@ -31,6 +31,12 @@ not** have to exist as physical files and directories on the file system:
 for example, a package and its resources can be imported from a zip file using
 :py:mod:`zipimport`.
 
+.. warning::
+
+   :mod:`importlib.resources` follows the same security model as the built-in
+   :func:`open` function. Passing untrusted inputs to the functions
+   in this module is unsafe.
+
 .. note::
 
    The standalone backport of this module provides more information