Fixed docs

Author: antonbabenko

README.md

@@ -91,6 +91,7 @@ No modules.
 | [aws_iam_policy_document.this](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/iam_policy_document) | data source |
 | [aws_partition.current](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/partition) | data source |
 | [aws_region.current](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/region) | data source |
+| [aws_service_principal.rds](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/service_principal) | data source |
 
 ## Inputs