Add note to _vendor/README.rst about pkg_resources patch.
@@ -100,7 +100,8 @@ Modifications
* ``setuptools`` is completely stripped to only keep ``pkg_resources``.
* ``pkg_resources`` has been modified to import its dependencies from
- ``pip._vendor``.
+ ``pip._vendor``, and to use the vendored copy of ``platformdirs``
+ rather than ``appdirs`.
* ``packaging`` has been modified to import its dependencies from
``pip._vendor``.
* ``html5lib`` has been modified to import six from ``pip._vendor``, to prefer
