diff --git a/containers/admin/v1.21/README.md b/containers/admin/v1.21/README.md
index cb55405d..601b1208 100644
--- a/containers/admin/v1.21/README.md
+++ b/containers/admin/v1.21/README.md
@@ -1,25 +1,31 @@
-! Ensure your Kube context points to the correct cluster !
+*Ensure your Kube context points to the correct cluster !!!*
 
-# Trigger the cluster upgrade
+1. Trigger the cluster upgrade:  
 `./upgrade_121.sh`
 
-# Upgrade CFN stacks for the control plane and all worker groups
+2. Upgrade CFN stacks for the control plane and all worker groups
+Change Kubernetes version in controller config from `1.20.X` to `1.21.9`
 
-# Reboot controller(s) one by one
+3. Reboot controller(s) one by one
+Wait each time for controller to join and all pods running.
+Might take a while ...
 
-# Patch current deployments, blocking ArgoCD otherwise
+4. Patch current deployments, blocking ArgoCD otherwise  
 `./kubezero_121.sh`
 
-# Migrate ArgoCD config for the cluster
-`./migrate_argo.sh "cluster/env/kubezero/application.yaml"`
-
-Adjust as needed, eg. ensure eck-operator is enabled if needed.
-git add / commit / push
-
+5. Migrate ArgoCD config for the cluster  
+`./migrate_argo.sh <cluster/env/kubezero/application.yaml>`  
+Adjust as needed, eg. ensure eck-operator is enabled if needed.  
+git add / commit / push  
 Watch ArgoCD do its work.
 
-# Replace worker nodes 
+6. Replace worker nodes
+Eg. by doubling `desired` for each worker ASG,  
+once all new workers joined, drain old workers one by one,  
+finally reset `desired` for each worker ASG which will terminate the old workers.
 
 ## Known issues
-- pods seem stuck, eg. fluent-bit on workers shows NotReady *after* control nodes have been ugpraded  
+On old/current workers, until workers get replaced:
+
+If pods seem stuck, eg. fluent-bit shows NotReady *after* control nodes have been upgraded  
   -> restart `kube-proxy` on the affected workers