[1.8.x] Fixed #25351 -- Added example for database test settings to docs.

Backport of cf99bae53a from master

docs/ref/settings.txt

@@ -623,8 +623,22 @@ TEST
 Default: ``{}``
 
 A dictionary of settings for test databases; for more details about the
-creation and use of test databases, see :ref:`the-test-database`. The
-following entries are available:
+creation and use of test databases, see :ref:`the-test-database`.
+
+Here's an example with a test database configuration::
+
+    DATABASES = {
+        'default': {
+            'ENGINE': 'django.db.backends.postgresql',
+            'USER': 'mydatabaseuser',
+            'NAME': 'mydatabase',
+            'TEST': {
+                'NAME': 'mytestdatabase',
+            },
+        },
+    }
+
+The following keys in the ``TEST`` dictionary are available:
 
 .. setting:: TEST_CHARSET