Use kubectl scale (#932)

* Use kubectl scale

Signed-off-by: JenTing Hsiao <jenting.hsiao@suse.com>

* Apply suggestions from code review

Co-authored-by: c3y1huang <chin-ya.huang@suse.com>

Co-authored-by: c3y1huang <chin-ya.huang@suse.com>

adoc/deployment-sysreqs.adoc

@@ -436,25 +436,21 @@ After deployment, if the number of healthy nodes falls below the number required
 
 The following describes two methods for replica management if you wish to work with a cluster below the default replica size requirement.
 
-===== Reduce replica number
+===== Update replica number
 
-One method is to reduce the number of overall replicas being created by a service.
+One method is to update the number of overall replicas being created by a service.
 Please consult the documentation of your respective service what the replica limits for proper high availability are.
 In case the replica number is too high for the cluster, you must increase the cluster size to provide more resources.
 
-. Reduce deployment replica size before node joining.
+. Update deployment replica size before node joining.
 +
 [NOTE]
 ====
 You can use the same steps to increase the replica size again if more resources become available later on.
 ====
 +
 ----
-kubectl -n kube-system edit deployment <NAME>
-
-# Example
-spec:
-  replicas: 2
+kubectl -n kube-system scale --replicas=<DESIRED_REPLICAS> deployment <NAME>
 ----
 . Join new nodes.