docs: Added missing doc link
Added a link to the existing `how-to-use-virtio-fs-with-kata.md`.
Fixes
- [How to use Kata Containers and Containerd](containerd-kata.md)
- [How to use Kata Containers and CRI (containerd plugin) with Kubernetes](how-to-use-k8s-with-cri-containerd-and-kata.md)
+- [How to use Kata Containers with virtio-fs](how-to-use-virtio-fs-with-kata.md)
- [Kata Containers and service mesh for Kubernetes](service-mesh.md)
- [Kata Containers with Firecracker](https://github.com/kata-containers/documentation/wiki/Initial-release-of-Kata-Containers-with-Firecracker-support)
- [Kata Containers with NEMU](how-to-use-kata-containers-with-nemu.md)
