Remove more Django 1.8 references from docs

docs/advanced_topics/customisation/admin_templates.rst

@@ -4,9 +4,6 @@ Customising admin templates
 
 In your projects with Wagtail, you may wish to replace elements such as the Wagtail logo within the admin interface with your own branding. This can be done through Django's template inheritance mechanism.
 
-.. note::
-   Using ``{% extends %}`` in this way on a template you're currently overriding is only supported in Django 1.9 and above. On Django 1.8, you will need to use `django-overextends <https://github.com/stephenmcd/django-overextends>`_ instead.
-
 You need to create a ``templates/wagtailadmin/`` folder within one of your apps - this may be an existing one, or a new one created for this purpose, for example, ``dashboard``. This app must be registered in ``INSTALLED_APPS`` before ``wagtail.wagtailadmin``:
 
 .. code-block:: python

docs/advanced_topics/customisation/custom_user_models.rst

@@ -59,9 +59,6 @@ Template create.html:
       {% include "wagtailadmin/shared/field_as_li.html" with field=form.status %}
   {% endblock extra_fields %}
 
-.. note::
-   Using ``{% extends %}`` in this way on a template you're currently overriding is only supported in Django 1.9 and above. On Django 1.8, you will need to use `django-overextends <https://github.com/stephenmcd/django-overextends>`_ instead.
-
 Template edit.html:
 
 .. code-block:: html+django

docs/advanced_topics/jinja2.rst

@@ -13,7 +13,7 @@ Configuring Django
 
     Jinja2 tags were moved from "templatetags" into "jinja2tags" to separate them from Django template tags.
 
-Django needs to be configured to support Jinja2 templates. As the Wagtail admin is written using regular Django templates, Django has to be configured to use both templating engines. Wagtail supports the Jinja2 backend that ships with Django 1.8 and above. Add the following configuration to the ``TEMPLATES`` setting for your app:
+Django needs to be configured to support Jinja2 templates. As the Wagtail admin is written using regular Django templates, Django has to be configured to use both templating engines. Add the following configuration to the ``TEMPLATES`` setting for your app:
 
 .. code-block:: python
 

docs/advanced_topics/settings.rst

@@ -345,7 +345,7 @@ Unicode Page Slugs
 
   WAGTAIL_ALLOW_UNICODE_SLUGS = True
 
-By default, page slugs can contain any alphanumeric characters, including non-Latin alphabets (except on Django 1.8, where only ASCII characters are supported). Set this to False to limit slugs to ASCII characters.
+By default, page slugs can contain any alphanumeric characters, including non-Latin alphabets. Set this to False to limit slugs to ASCII characters.
 
 .. _WAGTAIL_AUTO_UPDATE_PREVIEW:
 

docs/getting_started/integrating_into_django.rst

@@ -5,7 +5,7 @@ Integrating Wagtail into a Django project
 
 Wagtail provides the ``wagtail start`` command and project template to get you started with a new Wagtail project as quickly as possible, but it's easy to integrate Wagtail into an existing Django project too.
 
-Wagtail is currently compatible with Django 1.8, 1.10 and 1.11. First, install the ``wagtail`` package from PyPI:
+Wagtail is currently compatible with Django 1.11. First, install the ``wagtail`` package from PyPI:
 
 .. code-block:: console