Update documentation for database connection parameters

Hello,

I've noticed that your database connection documentation is outdated, which causes confusion for users like me. I kindly request that you update it with current connection parameters and descriptions. It would also be helpful if you could include this updated documentation in docstrings for easier access.

[Link to current documentation](https://docs.edgedb.com/libraries/python/api/asyncio_client)

[Link to relevant code](https://github.com/edgedb/edgedb-python/blob/master/edgedb/asyncio_client.py#L402)