update README to reference docker v2.20.0 tag (#9334) (#9348)

Signed-off-by: hang.jiang <hang.jiang@daocloud.io>

Signed-off-by: hang.jiang <hang.jiang@daocloud.io>
Co-authored-by: Alex <payback159@gmail.com>

README.md

@@ -57,10 +57,10 @@ A simple way to ensure you get all the correct version of Ansible is to use the
 You will then need to use [bind mounts](https://docs.docker.com/storage/bind-mounts/) to get the inventory and ssh key into the container, like this:
 
 ```ShellSession
-docker pull quay.io/kubespray/kubespray:v2.19.1
+docker pull quay.io/kubespray/kubespray:v2.20.0
 docker run --rm -it --mount type=bind,source="$(pwd)"/inventory/sample,dst=/inventory \
   --mount type=bind,source="${HOME}"/.ssh/id_rsa,dst=/root/.ssh/id_rsa \
-  quay.io/kubespray/kubespray:v2.19.1 bash
+  quay.io/kubespray/kubespray:v2.20.0 bash
 # Inside the container you may now run the kubespray playbooks:
 ansible-playbook -i /inventory/inventory.ini --private-key /root/.ssh/id_rsa cluster.yml
 ```