Fix docs/examples with cast_results() method on DSISClient

[joannaszalas]

1. example suggesting it is a query method, while it is on client.
2. this example suggests twice that the response has a value key, but I am getting a generator object from client.executeQuery(query), so it is a bit misleading. Unless there can be different response types here?

Didn't check for more examples, but might be worth checking.