docs: Recommend using GitHub OIDC role assumption over hardcoded access keys (#111)

Author: jplock

README.md

@@ -27,8 +27,8 @@ jobs:
           token: ${{ secrets.GITHUB_TOKEN }}
       - uses: aws-actions/configure-aws-credentials@v2
         with:
-          aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
-          aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          role-to-assume: ${{ secrets.ASSUME_ROLE_ARN }}
+          role-session-name: ci
           aws-region: us-east-2
       # Build inside Docker containers
       - run: sam build --use-container