Removed all uses of STATIC_URL from code samples, replaced with static().

Concatinating with settings.STATIC_URL is no longer reccomended for creating
URLs to static resources, because it doesn't take the configured storage engine
into account. For example, a site using S3 to store its static files will need
static URLs that link out to S3, rather than relative URLs within the same
domain.

I replaced it with django.contrib.staticfiles.templatetags.staticfiles.static()
in python example code, and the {% static %} tag in template examples.

docs/advanced_topics/customisation/branding.rst

@@ -39,9 +39,10 @@ The template blocks that are available to be overridden are as follows:
 To replace the default logo, create a template file ``dashboard/templates/wagtailadmin/base.html`` that overrides the block ``branding_logo``::
 
     {% overextends "wagtailadmin/base.html" %}
+    {% load staticfiles %}
     
     {% block branding_logo %}
-        <img src="{{ STATIC_URL }}images/custom-logo.svg" alt="Custom Project" width="80" />
+        <img src="{% static 'images/custom-logo.svg' %}" alt="Custom Project" width="80" />
     {% endblock %}
 
 ``branding_favicon``
@@ -50,9 +51,10 @@ To replace the default logo, create a template file ``dashboard/templates/wagtai
 To replace the favicon displayed when viewing admin pages, create a template file ``dashboard/templates/wagtailadmin/admin_base.html`` that overrides the block ``branding_favicon``::
 
     {% overextends "wagtailadmin/admin_base.html" %}
+    {% load staticfiles %}
 
     {% block branding_favicon %}
-        <link rel="shortcut icon" href="{{ STATIC_URL }}images/favicon.ico" />
+        <link rel="shortcut icon" href="{% static 'images/favicon.ico' %}" />
     {% endblock %}
 
 ``branding_login``

docs/reference/hooks.rst

@@ -257,16 +257,17 @@ Hooks for customising the editing interface for pages and snippets.
 
   .. code-block:: python
 
+    from django.contrib.staticfiles.templatetags.staticfiles import static
     from django.utils.html import format_html
-    from django.conf import settings
 
     from wagtail.wagtailcore import hooks
 
     @hooks.register('insert_editor_css')
     def editor_css():
-      return format_html('<link rel="stylesheet" href="' \
-      + settings.STATIC_URL \
-      + 'demo/css/vendor/font-awesome/css/font-awesome.min.css">')
+        return format_html(
+            '<link rel="stylesheet" href="{}">',
+            static('demo/css/vendor/font-awesome/css/font-awesome.min.css')
+        )
 
 
 .. _insert_global_admin_css:
@@ -274,20 +275,18 @@ Hooks for customising the editing interface for pages and snippets.
 ``insert_global_admin_css``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Add additional CSS files or snippets to all admin pages.
+  Add additional CSS files or snippets to all admin pages.
 
-.. code-block:: python
-
-  from django.utils.html import format_html
-  from django.conf import settings
-
-  from wagtail.wagtailcore import hooks
-
-  @hooks.register('insert_global_admin_css')
-  def global_admin_css():
-    return format_html('<link rel="stylesheet" href="' \
-    + settings.STATIC_URL \
-    + 'my/wagtail/theme.css">')
+  .. code-block:: python
+  
+    from django.utils.html import format_html
+    from django.contrib.staticfiles.templatetags.staticfiles import static
+  
+    from wagtail.wagtailcore import hooks
+  
+    @hooks.register('insert_global_admin_css')
+    def global_admin_css():
+        return format_html('<link rel="stylesheet" href="{}">', static('my/wagtail/theme.css'))
 
 
 .. _insert_editor_js: