[Task]: Update BigQuery IO Docs: BigQuery IO supports READ_API

### What needs to happen?

https://github.com/apache/beam/blob/master/sdks/python/apache_beam/io/gcp/bigquery.py

Looks like BQ Read API supported. But, docs do not indicate this.

The docs: https://beam.apache.org/documentation/io/built-in/google-bigquery/

Say "# The SDK for Python does not support the BigQuery Storage API." in the Python section of: https://beam.apache.org/documentation/io/built-in/google-bigquery/#updating-your-code

### Issue Priority

Priority: 2 (default / most normal work should be filed as P2)

### Issue Components

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