Update README.md description to match other official providers (#10982)
Update README.md description to match other official providers (#10982)

See:
- https://github.com/terraform-providers/terraform-provider-azurerm/blob/master/README.md#terraform-provider-for-azure-resource-manager
- https://github.com/terraform-providers/terraform-provider-google/blob/master/README.md#terraform-provider-for-google-cloud-platform
- https://github.com/terraform-providers/terraform-provider-helm/blob/master/README.md#terraform-provider-for-helm
- https://github.com/terraform-providers/terraform-provider-kubernetes/blob/master/README.md#terraform-provider-for-kubernetes
kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,terraform-providers/terraform-provider-aws,kjmkznr/terraform-provider-aws