Start api directory, which will become a module.

api/types/doc.go

@@ -0,0 +1,9 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+// Package types holds the definition of the kustomization struct and
+// supporting structs.  It's the k8s API conformant object that describes
+// a set of generation and transformation operations to create and/or
+// modify k8s resources.
+// A kustomization file is a serialization of this struct.
+package types