[1.8.x] Fixed #25549 -- Documented auth_user_password_change URL.

Change                  ``{{ app_label }}_{{ model_name }}_change``       ``object_id``

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The ``UserAdmin`` provides a named URL:

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Page                    URL name                                          Parameters

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Password change         ``auth_user_password_change``                     ``user_id``

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These named URLs are registered with the application namespace ``admin``, and

with an instance namespace corresponding to the name of the Site instance.