Update developer guide with compatible yq version 3.* (kubeflow#1292)

docs/DEVELOPER_GUIDE.md

@@ -47,7 +47,7 @@ You must install these tools:
 1. [`kubectl`](https://kubernetes.io/docs/tasks/tools/install-kubectl/): For
    managing development environments.
 1. [`kustomize`](https://github.com/kubernetes-sigs/kustomize/) To customize YAMLs for different environments, requires v3.5.4+.
-1. [`yq`](https://github.com/mikefarah/yq) yq is used in the project makefiles to parse and display YAML output
+1. [`yq`](https://github.com/mikefarah/yq) yq is used in the project makefiles to parse and display YAML output. Please use yq version [`3.*`](https://github.com/mikefarah/yq/releases/tag/3.4.1). Latest yq version `4.*` has remove `-d` command so doesn't work with the scripts.
 
 ### Install Knative on a Kubernetes cluster