Add comment explaining AWS credential provider chain

Adds a comment explaining how AWS SDK resolves credentials using the default credential provider chain (environment variables, shared credentials files, and IAM roles). This may help developers who are unfamiliar with how credentials are automatically discovered by the SDK.

Author: saivarshithkothwali

javascriptv3/example_code/ses/src/libs/sesClient.js

@@ -14,6 +14,12 @@ sesClient.js is a helper function that creates an Amazon Simple Email Services (
 import { SESClient } from "@aws-sdk/client-ses";
 // Set the AWS Region.
 const REGION = "us-east-1";
+// Credentials are automatically resolved using the AWS SDK credential provider chain.
+// This includes:
+// - Environment variables (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY)
+// - Shared credentials file (~/.aws/credentials)
+// - IAM roles attached to compute services such as Amazon EC2, ECS, or AWS Lambda.
+// See: https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/setting-credentials-node.html
 // Create SES service object.
 const sesClient = new SESClient({ region: REGION });
 export { sesClient };