Remind user to deploy placement controller before running some test c…

…ases (open-cluster-management-io#47)

Signed-off-by: suigh <[email protected]>

CONTRIBUTING.md

@@ -59,25 +59,17 @@ Run integration testing
 make test-integration
 ```
 
-Run e2e testing.
-```shell
-go install github.com/openshift/imagebuilder/cmd/[email protected]
-
-export KUBECONFIG=</path/to/kubeconfig>
-
-make images
+Before running e2e/scalability testing, deploy the placement controller with corresponding steps from [PLACEMENT Doc](https://github.com/open-cluster-management-io/placement#deploy-the-placement-controller)
 
-kind load docker-image quay.io/open-cluster-management/placement:latest --name {your cluster name}
+Run e2e testing.
 
+```shell
 make test-e2e
 ```
 
 Run scalability testing if your PR has impact on the scalability
 
 ```shell
-Deploy the placement controller with corresponding steps from [PLACEMENT Doc](https://github.com/open-cluster-management-io/placement#deploy-the-placement-controller)
-
-
 make test-scalability
 ```