Is your feature request related to a problem? Please describe.

I'd like to use table-level IAM with the Google BigQuery client library.

The get_iam_policy and set_iam_policy methods are implemented

but not documented:

https://cloud.google.com/python/docs/reference/bigquery/latest/google.cloud.bigquery.client.Client

Describe the solution you'd like

In addition to doc strings for the methods, a sample similar to the Java sample at https://cloud.google.com/bigquery/docs/control-access-to-resources-iam#grant_access_to_a_table_or_view would be most welcome.

Describe alternatives you've considered

N/A

Additional context

N/A