Adding a document listing the k8s workloads supported by Yunikorn

Requirement:
Adding a document named "K8s workloads" in workload documents.
This document describes supported k8s workloads and examples of them.

Background:
Most examples of the k8s workload in yunikorn website is the pod.
Actually, yunikorn also support other k8s workloads such as the job, the statefulSet and the daemonset.
The ability of Yunikorn to schedule these k8s workloads is validated in the [e2e test](https://github.com/apache/yunikorn-k8shim/tree/master/test/e2e/admission_controller).