provider/aws: Fix error message returned when an invalid SSM document type is provided. The original error appears to have been copied from the CodeBuild resource and provides incorrect information about valid types.

builtin/providers/aws/resource_aws_ssm_document.go

@@ -384,7 +384,7 @@ func validateAwsSSMDocumentType(v interface{}, k string) (ws []string, errors []
 	}
 
 	if !types[value] {
-		errors = append(errors, fmt.Errorf("CodeBuild: Arifacts Namespace Type can only be NONE / BUILD_ID"))
+		errors = append(errors, fmt.Errorf("Document type %s is invalid. Valid types are Command, Policy or Automation", value))
 	}
 	return
 }