Added important note about using url() on older versions of django, but switched the examples to re_path as to comply with Django docs for 2.0 and later.
Currently queries executed in the hooks don't run in the transaction
with the page deletion query and it's harder to write hook without
copying the whole view if you want to keep queries running in the hooks
integral with page deletion.
According to a google search I just did, it seems a lot of people have forgotten to add ``Disallow: /admin`` in their robots.txt (or forgot to add robots.txt) at all.
Adding this meta tag into the head of all admin pages should prevent any admin pages being indexed even if this was missed.
The behaviour of `has_usable_password` has changed in Django 2.1, such that `None` is no longer considered a 'non-usable' password: https://docs.djangoproject.com/en/2.1/ref/contrib/auth/#django.contrib.auth.models.User.has_usable_password
As a consequence of the fix applied in Django https://code.djangoproject.com/ticket/28718 , Wagtail users created without a password will now be able to complete the password reset process to gain access to Wagtail. Sites that do not want this behaviour (e.g. because those users should be using an LDAP login instead) should disable password changes via WAGTAIL_PASSWORD_MANAGEMENT_ENABLED and WAGTAIL_PASSWORD_RESET_ENABLED.
* Update integrating_into_django.rst
flaw in url, was still referencing depreciated method, fixed.
* Update integrating_into_django.rst
Add important notice that versions of Django earlier than 2.0 require url() instead of re_path()
By optionally passing the request object to Page.get_sitemap_urls() it
will now use the cached site root on the request object instead of
retrieving it for each call. This cuts the number of queries required
for a sitemap roughly in half.
