Add build status, usage to README

Author: swinton

README.md

@@ -2,6 +2,24 @@
 
 Configure AWS credential environment variables for use in other GitHub Actions.
 
+<a href="https://github.com/aws/configure-aws-credentials-for-github-actions"><img alt="GitHub Actions status" src="https://github.com/aws/configure-aws-credentials-for-github-actions/workflows/test-local/badge.svg"></a>
+
+This action adds configuration required by [the AWS CLI](https://aws.amazon.com/cli/) for use in subsequent actions.
+
+## Usage
+
+Add the following step to your workflow:
+
+```yaml
+    - name: Configure AWS Credentials
+      uses: aws/configure-aws-credentials-for-github-actions
+      with:
+        aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
+        aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+        aws-default-region: us-east-2
+        aws-default-output: json
+```
+
 ## License Summary
 
 This code is made available under the MIT license.