PostgreSQL range types need better documentation

[David Lord]

When initializing a model, what is the correct value to pass to a range column? Prompted by this StackOverflow question, I looked at the tests and found they were using a type helper from psycopg2. Is that the proper way, or is there something on SQLAlchemy's side too? Either way, it's not made clear in the docs.

[Mike Bayer]

I can point this to the author of the range system @chrisw

[Mike Bayer]

Merged in chrisw/sqlalchemy/more_range_docs (pull request #20)

more docs for using psycopg2 range types, specifically instantiating models with them

fixes #3046

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