Followup to https://github.com/elastic/apm-aws-lambda/issues/389 **Is your feature request related to a problem? Please describe.** documentation for setting up the aws secret manager was quite hard to follow **Describe the solution you'd like** Make it clear/consistent with the smoke test we recently added **Describe alternatives you've considered** A clear and concise description of any alternative solutions or features you've considered. **Additional context** Add any other context or screenshots about the feature request here.