Updating documentation on using Node.js 16 or 18 (which requires inst…

…alling AWS SDK v2).

README.md

@@ -59,7 +59,8 @@ the email forwarding mapping from original destinations to new destination.
 2. In AWS Lambda, add a new function and skip selecting a blueprint.
 
  - Name the function "SesForwarder" and optionally give it a description. Ensure
- Runtime is set to Node.js 18.x or Node.js 16.x.
+ Runtime is set to Node.js 16.x. (Node.js 18.x can be used if the AWS SDK v2
+ module is also installed.)
 
  - For the Lambda function code, either copy and paste the contents of
  `index.js` into the inline code editor or zip the contents of the repository