docs: Add swap annotations introduction

Add swap annotations introduction of
`io.katacontainers.config.hypervisor.enable_guest_swap`,
`io.katacontainers.container.resource.swappiness"` and
`io.katacontainers.container.resource.swap_in_bytes"` to
how-to-set-sandbox-config-kata.md.

Fixes: kata-containers#2201

Signed-off-by: Hui Zhu <teawater@antfin.com>

docs/how-to/how-to-set-sandbox-config-kata.md

@@ -91,6 +91,13 @@ There are several kinds of Kata configurations and they are listed below.
 | `io.katacontainers.config.hypervisor.virtio_fs_cache` | string | the cache mode for virtio-fs, valid values are `always`, `auto` and `none` |
 | `io.katacontainers.config.hypervisor.virtio_fs_daemon` | string | virtio-fs `vhost-user` daemon path |
 | `io.katacontainers.config.hypervisor.virtio_fs_extra_args` | string | extra options passed to `virtiofs` daemon |
+| `io.katacontainers.config.hypervisor.enable_guest_swap` | `boolean` | enable swap in the guest |
+
+## Container Options
+| Key | Value Type | Comments |
+|-------| ----- | ----- |
+| `io.katacontainers.container.resource.swappiness"` | `uint64` | specify the Resources.Memory.Swappiness |
+| `io.katacontainers.container.resource.swap_in_bytes"` | `int64` | specify the Resources.Memory.Swap |
 
 # CRI-O Configuration
 
@@ -100,11 +107,12 @@ In case of CRI-O, all annotations specified in the pod spec are passed down to K
 
 For containerd, annotations specified in the pod spec are passed down to Kata
 starting with version `1.3.0` of containerd. Additionally, extra configuration is
-needed for containerd, by providing a `pod_annotations` field in the containerd config
-file.  The `pod_annotations` field is a list of annotations that can be passed down to
-Kata as OCI annotations. It supports golang match patterns. Since annotations supported
-by Kata follow the pattern `io.katacontainers.*`, the following configuration would work
-for passing annotations to Kata from containerd:
+needed for containerd, by providing `pod_annotations` field and
+`container_annotations` field in the containerd config
+file.  The `pod_annotations` field and `container_annotations` field are two lists of
+annotations that can be passed down to Kata as OCI annotations. They support golang match
+patterns. Since annotations supported by Kata follow the pattern `io.katacontainers.*`,
+the following configuration would work for passing annotations to Kata from containerd:
 
 ```
 $ cat /etc/containerd/config
@@ -113,6 +121,7 @@ $ cat /etc/containerd/config
          [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.kata]
            runtime_type = "io.containerd.kata.v2"
            pod_annotations = ["io.katacontainers.*"]
+           container_annotations = ["io.katacontainers.*"]
 ....
 
 ```