Use AWS_REGION environment variable when available

[jwarchol]

Are you open to using the typical AWS_REGION environment variable for the selection of region before falling back to the hard-coded "us-west-2" value?

[jwerre]

Is there any reason you can't set AWS_REGION as the region? Something like:

const config = require('secrets').secretSync({
	region: process.env.AWS_REGION || 'us-east-1',
	id: '/my-co/apis/',
});