docs/provider: Minor wording updates in Maintaining Guide
docs/provider: Minor wording updates in Maintaining Guide

Reference: https://github.com/terraform-providers/terraform-provider-aws/pull/9332

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