docs: client_protocol_version missing from Connection Parameters table

[terellmcqueen]

The README references client_protocol_version under "Client Transfer Protocol," stating it can modify the protocol version. However, this parameter is:

1. Absent from the Connection Parameters table
2. Has no usage example or valid values documented

Suggested addition to the parameters table:

Parameter	Type	Default	Description
client_protocol_version	int	2	Controls the wire protocol version for data transfer

Example:

conn = redshift_connector.connect(
    host='cluster.abc123.us-east-1.redshift.amazonaws.com',
    database='dev',
    user='admin',
    password='***',
    client_protocol_version=2
)

Happy to open a PR if maintainers can confirm the valid values.