Add codegen::register to hack/update-codegen.sh

Co-authored-by: Joe Betz <[email protected]>
Signed-off-by: Lionel Jouin <[email protected]>

Kubernetes-commit: 5fa72a8c1db08e7b43bd29202c3c4d25b6d33bc6

Author: LionelJouin

cmd/register-gen/output_tests/simpletype/doc.go

@@ -14,5 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// +k8s:register-gen=simpletype
+
 // +groupName=simpletype.foo.bar
 package simpletype