[1.8.x] Fixed some code blocks indentation in GIS docs.

Backport of dbaa1a6b59 from master

docs/ref/contrib/gis/feeds.txt

@@ -31,9 +31,9 @@ API Reference
    base class, GeoDjango's ``Feed`` class provides
    the following overrides.  Note that these overrides may be done in multiple ways::
 
-       from django.contrib.gis.feeds import Feed
+        from django.contrib.gis.feeds import Feed
 
-       class MyFeed(Feed):
+        class MyFeed(Feed):
 
             # First, as a class attribute.
             geometry = ...

docs/ref/contrib/gis/testing.txt

@@ -132,11 +132,11 @@ in :mod:`django.contrib.gis`::
             'NAME': 'geodjango',
             'USER': 'geodjango',
         },
-       'other': {
+        'other': {
             'ENGINE': 'django.contrib.gis.db.backends.postgis',
             'NAME': 'other',
             'USER': 'geodjango',
-       }
+        },
     }
 
     SECRET_KEY = 'django_tests_secret_key'

docs/ref/contrib/gis/tutorial.txt

@@ -107,7 +107,7 @@ file. Edit the database connection settings to match your setup::
              'ENGINE': 'django.contrib.gis.db.backends.postgis',
              'NAME': 'geodjango',
              'USER': 'geo',
-         }
+        },
     }
 
 In addition, modify the :setting:`INSTALLED_APPS` setting to include
@@ -122,7 +122,7 @@ and ``world`` (your newly created application)::
         'django.contrib.messages',
         'django.contrib.staticfiles',
         'django.contrib.gis',
-        'world'
+        'world',
     )
 
 Geographic Data