Docs: fix custom_dns_configuration_cluster_aws (#860)

* Docs: fix custom_dns_configuration_cluster_aws

The import of this resource should performed using the project ID, not the auditing ID.

* Link update to OpenAPI Docs

Co-authored-by: Zuhair Ahmed <[email protected]>

Author: tooooots

website/docs/r/custom_dns_configuration_cluster_aws.markdown

@@ -33,10 +33,10 @@ resource "mongodbatlas_custom_dns_configuration_cluster_aws" "test" {
 
 
 ## Import
-Custom DNS Configuration for Atlas Clusters on AWS must be imported using auditing ID, e.g.
+Custom DNS Configuration for Atlas Clusters on AWS must be imported using Project ID, e.g.
 
 ```
 $ terraform import mongodbatlas_custom_dns_configuration_cluster_aws.test 1112222b3bf99403840e8934
 ```
 
-See detailed information for arguments and attributes: [MongoDB API Custom DNS Configuration for Atlas Clusters on AWS](https://docs.atlas.mongodb.com/reference/api/aws-custom-dns)
+See detailed information for arguments and attributes: [MongoDB API Custom DNS Configuration for Atlas Clusters on AWS](https://www.mongodb.com/docs/atlas/reference/api-resources-spec/#tag/Custom-DNS-for-Atlas-Clusters-Deployed-to-AWS)