docs/provider: Additional information about new regions in Maintaining Guide
docs/provider: Additional information about new regions in Maintaining Guide

kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,terraform-providers/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,kjmkznr/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws