feat(train): add new command to interact with aws and train models

vendor/github.com/aws/smithy-go/document.go

@@ -0,0 +1,10 @@
+package smithy
+
+// Document provides access to loosely structured data in a document-like
+// format.
+//
+// Deprecated: See the github.com/aws/smithy-go/document package.
+type Document interface {
+	UnmarshalDocument(interface{}) error
+	GetValue() (interface{}, error)
+}