documentation: Add documentation of the IAM permissions needed to use the starter toolkit

### Description
Customers want to use least privilege when building agents with the starter toolkit. The documentation should provide a sample IAM policy for meeting the minimum permissions to use the starter toolkit.

No documentation file or test is named. Start by locating the starter toolkit's documentation and any existing IAM or permissions guidance, then document a sample policy containing the minimum permissions needed to use the toolkit. Done means users can identify and apply a least-privilege policy from the documentation.

Written by the indexing model from the issue text.