AWS role arn is a supported variable but not in the document. Documentation update needed about how it works.

**Describe the bug**

**To reproduce**

**Expected behavior**

**Screenshots**

**Your Environment**

- On-prem or cloud based?:
- Azure DevOps version:
- AWS Toolkit for Azure DevOps version:

**Additional context**

No documentation file, test, or entry point is named. Start by locating the documentation and the supported AWS role ARN variable, then confirm how it works from the existing project context. Done means the relevant documentation explains the variable and its behavior.

Written by the indexing model from the issue text.