chore(engines): add advisory for Node.js >=16.0.0 support

[trivikr]

Issue #, if available:
Refs: aws/aws-sdk-js-v3#1558

npmjs docs: https://docs.npmjs.com/files/package.json#engines

Unless the user has set the engine-strict config flag, this field is advisory only and will only produce warnings when your package is installed as a dependency.

Description of changes:
add advisory for Node.js >=10.0.0 support

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[texastony]

@trivikr do we still need this PR?
Should we update it to >= 16?

[trivikr]

Should we update it to >= 16?

The version needs to be the minimal version supported by the package.
As of #678, it's Node 16, as long as you're releasing new major version v5.0.0