Update practices.rst

With this modification scrapy runs the spider with project settings. The previous example ran only with default settings resulting in ignoring all user settings as pipelines for example.
Merge pull request #399 from irgmedeiros/patch-1

Update practices.rst
Added dynamic creation of item classes to practices.rst.
Merge pull request #401 from LorenDavie/master

Added dynamic creation of item classes to practices.rst. Issue
Corrected typo.
Merge pull request #402 from LorenDavie/master

Corrected typo.
docs: minor tidy up sample code and missing shell prompts.
docs: added section regarding setting up django's settings.
Merge pull request #404 from darkrho/djangoitem-docs

Add a section to DjangoItem docs page regarding setting up Django's settings.
Handling inconsistencies among Twisted releases
Merge pull request #406 from nopper/master

Handling inconsistencies among Twisted releases
updated required twisted version to 10.0