[Doc] Minor fix to MKP secret setup guide (#2576)

* fix doc

* apply suggestion

* split line

manifests/gcp_marketplace/guide.md

@@ -38,7 +38,8 @@ Then you can create a service account with the necessary IAM permissions
 export SA_NAME=<my-account>
 export NAMESPACE=<namespace-where-kfp-was-installed>
 # Create service account
-gcloud iam service-accounts create $SA_NAME --display-name $SA_NAME --project "$PROJECT_ID"
+gcloud iam service-accounts create $SA_NAME \
+  --display-name $SA_NAME --project "$PROJECT_ID"
 # Grant permissions to the service account by binding roles
 gcloud projects add-iam-policy-binding $PROJECT_ID \
   --member=serviceAccount:$SA_NAME@$PROJECT_ID.iam.gserviceaccount.com \
@@ -59,13 +60,10 @@ and store the service account credential as a Kubernetes secret `user-gcp-sa` in
 # Create credential for the service account
 gcloud iam service-accounts keys create application_default_credentials.json --iam-account $SA_NAME@$PROJECT_ID.iam.gserviceaccount.com
 
-# Make sure the secret is created under the correct namespace.
-kubectl config set-context --current --namespace=$NAMESPACE
-
 # Attempt to create a k8s secret. If already exists, override.
 kubectl create secret generic user-gcp-sa \
   --from-file=user-gcp-sa.json=application_default_credentials.json \
-  --dry-run -o yaml  |  kubectl apply -f -
+  -n $NAMESPACE --dry-run -o yaml  |  kubectl apply -f -
 ```
 Remove the private key file if needed
 ```