AmazonBedrockExecutionRoleForAgents_SageMakerQA does not have enough permissions run this workshops.

Hello,

I was running this workshops and ran into problems asking questions to Bedrock. I turns out that `AmazonBedrockExecutionRoleForAgents_SageMakerQA` has only permissions to use SageMaker.

I had to add following permission to run this workshop successfully;
- Invoke Bedrock Model
- `bedrock:Retrieve` on our knowledge base

I believe `template.yml` needs to be updated to add `bedrock:InvokeModel` permissions on foundation models, and the steps to add `bedrock:Retrieve` permission on a new knowledge base should be added in the instructions.

Thanks,

Start by reviewing template.yml and the workshop instructions to see how AmazonBedrockExecutionRoleForAgents_SageMakerQA is defined and how knowledge bases are created. Done means the role can invoke Bedrock foundation models and the instructions explain how to grant bedrock:Retrieve access to a new knowledge base.

Written by the indexing model from the issue text.