1. update clientset, deepcopy using code-generator

2. add a dummy file tools.go to force "go mod vendor" to see
code-generator as dependencies
3. add a script to update CRD
4. add a README to document CRD updating steps
run go mod tidy
update README

vendor/k8s.io/kube-openapi/pkg/generators/README.md

@@ -0,0 +1,49 @@
+# Generate OpenAPI definitions
+
+- To generate definition for a specific type or package add "+k8s:openapi-gen=true" tag to the type/package comment lines.
+- To exclude a type or a member from a tagged package/type, add "+k8s:openapi-gen=false" tag to the comment lines.
+
+# OpenAPI Extensions
+
+OpenAPI spec can have extensions on types. To define one or more extensions on a type or its member
+add `+k8s:openapi-gen=x-kubernetes-$NAME:$VALUE` to the comment lines before type/member. A type/member can
+have multiple extensions. The rest of the line in the comment will be used as $VALUE so there is no need to
+escape or quote the value string. Extensions can be used to pass more information to client generators or
+documentation generators. For example a type might have a friendly name to be displayed in documentation or
+being used in a client's fluent interface.
+
+# Custom OpenAPI type definitions
+
+Custom types which otherwise don't map directly to OpenAPI can override their
+OpenAPI definition by implementing a function named "OpenAPIDefinition" with
+the following signature:
+
+```go
+	import openapi "k8s.io/kube-openapi/pkg/common"
+
+	// ...
+
+	type Time struct {
+		time.Time
+	}
+
+	func (_ Time) OpenAPIDefinition() openapi.OpenAPIDefinition {
+		return openapi.OpenAPIDefinition{
+			Schema: spec.Schema{
+				SchemaProps: spec.SchemaProps{
+					Type:   []string{"string"},
+					Format: "date-time",
+				},
+			},
+		}
+	}
+```
+
+Alternatively, the type can avoid the "openapi" import by defining the following
+methods. The following example produces the same OpenAPI definition as the
+example above:
+
+```go
+    func (_ Time) OpenAPISchemaType() []string { return []string{"string"} }
+    func (_ Time) OpenAPISchemaFormat() string { return "date-time" }
+```