Include location parameter in the body example

https://github.com/GoogleCloudPlatform/workflows-demos/blob/4c4fbd91317f3a0293092d27b37eda1008403af0/bigquery-parallel/workflow-parallel.yaml#L44

Based on [QueryRequest Docs](https://cloud.google.com/workflows/docs/reference/googleapis/bigquery/v2/Overview#QueryRequest) and my tests, **location** atribute should be provided in the example for user convinience. It is not required, but it will be commonly required (e.g. customer using multi-regional datasets).

````yaml
body:
location: us #See details at https://cloud.google.com/bigquery/docs/locations#specifying_your_location
useLegacySql: false
useQueryCache: false
timeoutMs: 30000
# Find top 100 titles with most views on Wikipedia
query: ${
````

Open bigquery-parallel/workflow-parallel.yaml at line 44 and compare the body with the linked QueryRequest documentation. Add the optional location example shown in the issue, then verify the YAML remains valid and the BigQuery workflow example still reflects the intended request body.

Written by the indexing model from the issue text.