Integrating Wagtail into a Django project docs need updating

Found a bug? Please fill out the sections below. 👍

Issue Summary

A summary of the issue.

I think the docs are out of date:

from wagtail.admin import urls as wagtailadmin_urls
from wagtail.documents import urls as wagtaildocs_urls
from wagtail.core import urls as wagtail_urls

Should be:

from wagtail.admin import urls as wagtailadmin_urls
from wagtail.core import urls as wagtail_urls
from wagtail.documents import urls as wagtaildocs_urls

Steps to Reproduce

1. Follow the installation instructions to integrate into an existing Django project.

Any other relevant information. For example, why do you consider this a bug and what did you expect to happen instead?

• I have confirmed that this issue can be reproduced as described on a fresh Wagtail project: (yes / no)

Technical details

• Python version: Run python --version. Python 3.7.3
• Django version: Look in your requirements.txt, or run pip show django | grep Version. Version: 2.2.1
• Wagtail version: Look at the bottom of the Settings menu in the Wagtail admin, or run pip show wagtail | grep Version:. Version: 2.5.1
• Browser version: You can use http://www.whatsmybrowser.org/ to find this out.

[mathagician]

@loicteixeira I want to work on this issue. Can I take this?

[lb-]

Fixed and merged in https://github.com/wagtail/wagtail/commit/6a6555eb191b32e64de656605f9f5521dff07083