Update the source https://charts.helm.sh/stable of step 2 under the "Installing a Helm chart on an OpenShift Container Platform cluster" section. Correct the helm repo source by using a different example repo that is not deprecated.

Doc URL: https://docs.openshift.com/container-platform/4.9/applications/working_with_helm_charts/configuring-custom-helm-chart-repositories.html

Also, update the required field "version: x.x.x" in the Chart.yaml example file under step 4 of https://docs.openshift.com/container-platform/4.9/applications/working_with_helm_charts/configuring-custom-helm-chart-repositories.html#creating-a-custom-helm-chart-on-openshift_configuring-custom-helm-chart-repositories
(You can add "version: 0.0.1" to the Chart.yaml)