message: doc: nydus-fscache.md: fix up referenced container images
diff: # Nydus EROFS fscache user guide
  -This guide shows you how to use fscache-based EROFS nydus image service to launch docker containers with the fscache-enabled in-kernel erofs on-demand download feature.
  +This guide shows you how to use fscache-based EROFS nydus image service to launch containers with the fscache-enabled in-kernel EROFS on-demand download feature.
  ## Prepare the kernel
  -Be aware of using the fscache-enabled erofs kernel (Linux 5.19+), it can be built with the following steps:
  +Be aware of using the fscache-enabled EROFS kernel (Linux 5.19+), it can be built with the following steps:
  1. ``git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git`` \
  or (mirror in china): ``git://kernel.source.codeaurora.cn/pub/scm/linux/kernel/git/torvalds/linux.git``
  @@ -51,7 +51,7 @@ make
  1. Make sure your containerd version is 1.4 or above.
  -2. Get nydus snapshotter with erofs supported:
  +2. Get nydus snapshotter with EROFS supported:
  ```shell
  # clone code
  git clone https://github.com/containerd/nydus-snapshotter.git
  @@ -123,13 +123,21 @@ For more information on how to configure containerd to use nydus snapshotter ple
  ``` shell
  # pull nydus image
  -contrib/ctr-remote/bin/ctr-remote images rpull docker.io/hsiangkao/ubuntu:20.04-rafs-v6-docker
  +contrib/ctr-remote/bin/ctr-remote images rpull docker.io/hsiangkao/ubuntu:20.04-rafs-v6
  # run nydus image
  -ctr run --rm -t --snapshotter=nydus docker.io/hsiangkao/ubuntu:20.04-rafs-v6-docker ubuntu /bin/bash
  +ctr run --rm -t --snapshotter=nydus docker.io/hsiangkao/ubuntu:20.04-rafs-v6 ubuntu /bin/bash
  # remove nydus image
  -ctr images rm docker.io/hsiangkao/ubuntu:20.04-rafs-v6-docker
  +ctr images rm docker.io/hsiangkao/ubuntu:20.04-rafs-v6
  +```
  +
  +Some RAFS v6 referenced images (in Zstd algorithms):
  +```
  +docker.io/hsiangkao/ubuntu:20.04-rafs-v6
  +docker.io/hsiangkao/ubuntu:22.04-rafs-v6
  +docker.io/hsiangkao/wordpress:5.7-rafs-v6
  +docker.io/hsiangkao/wordpress:6.0-rafs-v6
  ```
  ## Try to convert a new image to RAFS v6
  