Proxy-side hostname resolution

Currently the driver sets the proxy type to ```socks5```, which performs the hostname resolution locally. However, it is also common to let the proxy do the hostname resolution with the ```socks5_hostname``` proxy type. It's possible to do this by specifying the proxy type in the connection string as ```proxyEndpoint=socks5h://proxy_host:port``` . This PR updates the connection parameters documentation to reflect that.