Fixed #601 -- Updated docs/model-api.txt unique_together section to say it's enforced at the database level.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@822 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/model-api.txt

@@ -248,18 +248,18 @@ Here are all available field types:
     uploaded files don't fill up the given directory).
 
     The admin represents this as an ``<input type="file">`` (a file-upload widget).
-    
-    Using a `FieldField` or an ``ImageField`` (see below) in a model takes a few 
+
+    Using a `FieldField` or an ``ImageField`` (see below) in a model takes a few
     steps:
-    
+
         1. In your settings file, you'll need to define ``MEDIA_ROOT``as the
            full path to a directory where you'd like Django to store uploaded
            files. (For performance, these files are not stored in the database.)
            Define ``MEDIA_URL`` as the base public URL of that directory. Make
            sure that this directory is writable by the Web server's user
            account.
-        
-        2. Add the ``FileField`` or ``ImageField`` to your model, making sure 
+
+        2. Add the ``FileField`` or ``ImageField`` to your model, making sure
            to define the ``upload_to`` option to tell Django to which
            subdirectory of ``MEDIA_ROOT`` it should upload files.
 
@@ -269,7 +269,7 @@ Here are all available field types:
            example, if your ``ImageField`` is called ``mug_shot``, you can get
            the absolute URL to your image in a template with ``{{
            object.get_mug_shot_url }}``.
-    
+
     .. _`strftime formatting`: http://docs.python.org/lib/module-time.html#l2h-1941
 
 ``FloatField``
@@ -302,7 +302,7 @@ Here are all available field types:
     width of the image each time a model instance is saved.
 
     Requires the `Python Imaging Library`_.
-    
+
     .. _Python Imaging Library: http://www.pythonware.com/products/pil/
 
 ``IntegerField``
@@ -721,7 +721,9 @@ Here's a list of all possible ``META`` options. No options are required. Adding
         unique_together = (("driver", "restaurant"),)
 
     This is a list of lists of fields that must be unique when considered
-    together. It's used in the Django admin.
+    together. It's used in the Django admin and is enforced at the database
+    level (i.e., the appropriate ``UNIQUE`` statements are included in the
+    ``CREATE TABLE`` statement).
 
 ``verbose_name``
     A human-readable name for the object, singular::