Make TODO clearer what action to take. [(#1963)](https://github.com/GoogleCloudPlatform/python-docs-samples/issues/1963)
Make TODO clearer what action to take. [(#1963)](https://github.com/GoogleCloudPlatform/python-docs-samples/issues/1963)

* Make TODO clearer what action to take.

Describe the variables to set explicitly (rather than "this"), as
suggested in internal CL 227863277.

* Use standard 'uncomment the variable below' for TODO

* Move variable below TODO.

googleapis/python-bigquery,googleapis/python-bigquery