Update setting-up-consumer.rst - AWS_S3 emphasize line fix

[samualblair]

Wrong line was being emphasized, line 12 was only a }, line 13 was the line that should be emphasized.

What issues does this address?

Documentation issue I found.

What does this change do?

Fixes documentation to highlight the correct line in example code.

Where should the reviewer start?

There is only 1 change to review.

Any background context?

https://clouddocs.f5.com/products/extensions/f5-telemetry-streaming/latest/setting-up-consumer.html There it was observed the wrong line was being highlighted.