CORS-4126: add descriptions for ap-southeast-6

The upgrade to AWS SDK v2 removes the ability to look up the region
description; thus, we are keeping the lookup map in the installer code.

This updates the lookup map to support new region ap-southeast-6

Reference

https://docs.aws.amazon.com/global-infrastructure/latest/regions/aws-regions.html

Author: tthvo

pkg/types/aws/regions.go

@@ -15,6 +15,7 @@ var (
 		"ap-northeast-2": "Asia Pacific (Seoul)",
 		"ap-southeast-1": "Asia Pacific (Singapore)",
 		"ap-southeast-2": "Asia Pacific (Sydney)",
+		"ap-southeast-6": "Asia Pacific (New Zealand)",
 		"ap-east-2":      "Asia Pacific (Taipei)",
 		"ap-southeast-7": "Asia Pacific (Thailand)",
 		"ap-northeast-1": "Asia Pacific (Tokyo)",