Typo in howto/static-files/

[Baptiste Mispelon]

In the first section of the "Managing static files (CSS, images)" documentation, the last two items of the list are both numbered 3 [1]

[1] ​https://docs.djangoproject.com/en/dev/howto/static-files/#configuring-static-files

[Tim Graham <timograham@…>]

In f71fdf83a8959f1b2131965cd893925d91ce81bc:

Fixed #20286 - Typo in static files docs.

Thanks bmispelon.

[Tim Graham <timograham@…>]

In d8d498347f8144ec075e76e57303e839ac9ab452:

[1.5.x] Fixed #20286 - Typo in static files docs.

Thanks bmispelon.

Backport of f71fdf83a8 from master