Fix documentation for "Writing custom django-admin command" to make closepoll.py work with code from cited tutorial

[anonymous]

s/example.polls.models/polls.models/
on ​https://docs.djangoproject.com/en/dev/howto/custom-management-commands/

As is, the code for polls/management/commands/closepoll.py shown near the
top of ​https://docs.djangoproject.com/en/dev/howto/custom-management-commands/
does not work with code from the tutorial cited at the top of the web page,
because the tutorial code does not use an "example" directory.

The solution is easy, remove "example." form the second line of the code
shown for polls/management/commands/closepoll.py.

[Stephen Muss]

documentation diff

[Claude Paroz]

In [17936]:

Fixed #18060 -- Corrected the import path of an example in custom management commands docs. Thanks smuss for the patch.