Add Node 20 as a runtime option in AWS

[Moshyfawn]

Ref: https://aws.amazon.com/blogs/compute/node-js-20-x-runtime-now-available-in-aws-lambda/

I was researching the support for AWS Lambda Node 20 and decided to make a small update to the AWS runtime section of the Project Manifest documentation since I was already checking when the support will be available for Architect.

[CLAassistant]

All committers have signed the CLA.

[ryanblock]

Thanks @Moshyfawn!