chore: add table of contents to README

Author: clareliguori

README.md

@@ -2,6 +2,20 @@
 
 Registers an Amazon ECS task definition and deploys it to an ECS service.
 
+**Table of Contents**
+
+<!-- toc -->
+
+- [Usage](#usage)
+- [Credentials and Region](#credentials-and-region)
+- [Permissions](#permissions)
+- [AWS CodeDeploy Support](#aws-codedeploy-support)
+- [Troubleshooting](#troubleshooting)
+- [License Summary](#license-summary)
+- [Security Disclosures](#security-disclosures)
+
+<!-- tocstop -->
+
 ## Usage
 
 ```yaml
@@ -138,6 +152,14 @@ The minimal permissions require access to CodeDeploy:
 }
 ```
 
+## Troubleshooting
+
+This action emits debug logs to help troubleshoot deployment failures.  To see the debug logs, create a secret named `ACTIONS_STEP_DEBUG` with value `true` in your repository.
+
 ## License Summary
 
 This code is made available under the MIT license.
+
+## Security Disclosures
+
+If you would like to report a potential security issue in this project, please do not create a GitHub issue.  Instead, please follow the instructions [here](https://aws.amazon.com/security/vulnerability-reporting/) or [email AWS security directly](mailto:aws-security@amazon.com).