Fix documentation formatting to fit within Terraform Registry

[mattdot]

• [x] Documentation callouts should use this syntax https://developer.hashicorp.com/terraform/registry/providers/docs#callouts
• [x] Consider subcategory: "Authentication" for authentication guides
• [x] Consider removing mirroring documentation
• [x] Validate docs using documentation preview tool https://registry.terraform.io/tools/doc-preview