link to sqlalchemy documentation

Direct link to SQLAlchemy docs on front page.
Description of what Flask-SQLAlchemy docs are.
Bump minimum SQLAlchemy version.

Author: davidism

docs/index.rst

@@ -6,7 +6,7 @@ Flask-SQLAlchemy
 .. module:: flask_sqlalchemy
 
 Flask-SQLAlchemy is an extension for `Flask`_ that adds support for
-`SQLAlchemy`_ to your application.  It requires SQLAlchemy 0.6 or
+`SQLAlchemy`_ to your application.  It requires SQLAlchemy 0.8 or
 higher.  It aims to simplify using SQLAlchemy with Flask by providing
 useful defaults and extra helpers that make it easier to accomplish common
 tasks.
@@ -16,4 +16,8 @@ tasks.
 .. _example sourcecode:
    http://github.com/mitsuhiko/flask-sqlalchemy/tree/master/examples/
 
+See `the SQLAlchemy documentation`_ to learn how to work with the ORM in depth.  The following documentation is a brief overview of the most common tasks, as well as the features specific to Flask-SQLAlchemy.
+
+.. _the SQLAlchemy documentation: http://docs.sqlalchemy.org/
+
 .. include:: contents.rst.inc