Fixed typo in docs/topics/http/sessions.txt

docs/topics/http/sessions.txt

@@ -221,7 +221,7 @@ You can edit it multiple times.
 
     .. method:: flush()
 
-      Delete the current session data from the session and delete the session
+      Deletes the current session data from the session and deletes the session
       cookie. This is used if you want to ensure that the previous session data
       can't be accessed again from the user's browser (for example, the
       :func:`django.contrib.auth.logout()` function calls it).