[zh] Fix task list

We now seem to have two sections on extending Kubernetes. This turns out
to be a folder name change problem after a closer investigation. The
English folder changed 'access-kubernetes-api' to 'extend-kubernetes',
but this change was not propagated to Chinese localization.

content/zh/docs/tasks/extend-kubernetes/custom-resources/_index.md

@@ -0,0 +1,4 @@
+---
+title: "使用自定义资源"
+weight: 10
+---