fix the incorrect instruction docs of "creation/update the ConfigMap"

doc link: https://yunikorn.apache.org/docs/next/developer_guide/deployment#createupdate-the-configmap

the example of Yunikorn-configs.yaml from `https://raw.githubusercontent.com/apache/yunikorn-k8shim/master/deployments/scheduler/yunikorn-configs.yaml`should be applied directly rather than creating the ConfigMap.

It seems to me the following changes are required.

1) "modify the content of yunikorn-configs.yaml file as needed, and create ConfigMap in kubernetes:" -> "modify the content of yunikorn-configs.yaml file as needed, and apply yunikorn-configs.yaml file in kubernetes:"

2) "kubectl create configmap yunikorn-configs --from-file=yunikorn-configs.yaml" -> "kubectl apply -f yunikorn-configs.yaml"