Add introspection example

[pydanny]

No description provided.

[jph00]

This is a great idea. A few suggestions to make it maybe easier for folks to understand:

• Do the initial table setup use plain SQL statements - i.e using db.q(). That way, it's more obvious I think what's going on, and you don't need the del stuff and explanation
• Before you do any of the globals() stuff, show how to manually use db.t. and dataclass to dynamically get the table objects and classes
• Then finally at the end explain that can be automated.