Update readme with security notification blurb (#122)

Author: bryan-aguilar

README.md

@@ -24,6 +24,10 @@ The [OpenTelemetry JavaScript SDK](https://github.com/open-telemetry/opentelemet
 
 For more information on OpenTelemetry, visit: https://opentelemetry.io/
 
+## Security issue notifications
+If you discover a potential security issue in this project we ask that you notify AWS/Amazon Security via our [vulnerability reporting page](http://aws.amazon.com/security/vulnerability-reporting/). Please do **not** create a public github issue.
+
+
 ## License
 
 This project is licensed under the Apache-2.0 License.