[Documentation Issue] Querying data (synchronous) code example is wrong

Page Name: bigquery-usage
Release: 0.11.0

``` python
>>> while retry_count > 0 and not job.complete:
...     retry_count -= 1
...     time.sleep(10)
...     query.reload()  # API request
```

`job` does not exist here and `query.reload()` method does not exist.
