[1.8.x] Fixed download instructions for cities shapefile

your geospatial data, in order for most of them to be useful you have

to have some data to work with.  If you're starting out and don't yet

have any data of your own to use, GeoDjango tests contain a number of

simple data sets that you can use for testing. You can download them here:

simple data sets that you can use for testing. You can download them here::

https://github.com/django/django/raw/master/tests/gis_tests/data/cities/cities.shp

    $ wget https://raw.githubusercontent.com/django/django/master/tests/gis_tests/data/cities/cities.{shp,prj,shx,dbf}

Vector Data Source Objects

==========================

   accessing the layers of data themselves, see the next section::

       >>> from django.contrib.gis.gdal import DataSource

       >>> ds = DataSource(CITIES_PATH)

       >>> ds = DataSource('/path/to/your/cities.shp')

       >>> ds.name

       '/path/to/your/cities.shp'

       >>> ds.layer_count                  # This file only contains one layer