Update docs a bit

docs/index.rst

@@ -144,10 +144,60 @@ using SQLAlchemy.::
 
 .. _models:
 
-Data Models
------------
+Models
+======
+
+Flask-Security assumes you'll be using libraries such as SQLAlchemy or 
+MongoEngine to define a data model that includes a `User` and `Role` model. The 
+fields on your models must follow a particular convention depending on the 
+functionality your app requires. Aside from this, you're free to add any 
+additional fields to your model(s) if you want. At the bear minimum your `User`
+and `Role` model should include the following fields:
+
+**User**
+
+* id
+* email
+* password
+* remember_token
+* active
+* authentication_token
+
+**Role**
+
+* id
+* name
+* description
+
+
+Additional Functionality
+------------------------
+
+Depending on the application's configuration, additional fields may need to be
+added to your `User` model.
+
+Confirmable
+^^^^^^^^^^^
+
+If you enable account confirmation by setting your application's 
+`SECURITY_CONFIRMABLE` configuration value to `True` your `User` model will 
+require the following additional field:
+
+* confirmed_at
+
+Trackable
+^^^^^^^^^
+
+If you enable user tracking by setting your application's `SECURITY_TRACKABLE` 
+configuration value to `True` your `User` model will require the following 
+additional fields:
+
+* last_login_at
+* current_login_at
+* last_login_ip
+* current_login_ip
+* login_count
 
-TODO: Describe models and required fields for various features
 
 .. _flask-script-commands: