feat(client-docdb): Add v2 smoke tests and smithy smokeTests trait for SDK testing.

Author: awstools

codegen/sdk-codegen/aws-models/docdb.json

@@ -4675,7 +4675,20 @@
           "outputToken": "Marker",
           "items": "DBEngineVersions",
           "pageSize": "MaxRecords"
-        }
+        },
+        "smithy.test#smokeTests": [
+          {
+            "id": "DescribeDBEngineVersionsSuccess",
+            "params": {},
+            "vendorParams": {
+              "region": "us-west-2"
+            },
+            "vendorParamsShape": "aws.test#AwsVendorParams",
+            "expect": {
+              "success": {}
+            }
+          }
+        ]
       }
     },
     "com.amazonaws.docdb#DescribeDBEngineVersionsMessage": {