Updated docs regarding QuerySet slicing and IndexError, in line with …

…r2859

git-svn-id: http://code.djangoproject.com/svn/django/trunk@2862 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/db-api.txt

@@ -335,18 +335,18 @@ return a list of every *second* object of the first 10::
     Entry.objects.all()[:10:2]
 
 To retrieve a *single* object rather than a list
-(e.g. ``SELECT foo FROM bar LIMIT 1``), using a simple index instead of a
+(e.g. ``SELECT foo FROM bar LIMIT 1``), use a simple index instead of a
 slice. For example, this returns the first ``Entry`` in the database, after
 ordering entries alphabetically by headline::
 
     Entry.objects.order_by('headline')[0]
 
-This is equivalent to::
+This is roughly equivalent to::
 
     Entry.objects.order_by('headline')[0:1].get()
 
-Note that either of these two examples will raise ``DoesNotExist`` if no
-objects match the given criteria.
+Note, however, that the first of these will raise ``IndexError`` while the 
+second will raise ``DoesNotExist`` if no objects match the given criteria.
 
 QuerySet methods that return new QuerySets
 ------------------------------------------