Silence output from helm repo add

[mogul]

The helm command produces output on:

• stderr: If there's no kubeconfig present, it will complain
• stdout: It will notify you that the repo was added
• stdout: It will notify you when helm plugins are installed

This output prepends the otherwise clean output of the terraform command that gets executed. That results in problems for things like wrapper scripts, eg https://github.com/abdennour/eks-training/blob/347deefacd3b55433ae2d09a0a9824c53257c027/run-docker-compose.sh#L4

[abdennour]

Give it 2 hours at most, and all updated images will be deployed on Dockerhub automatically.

[abdennour]

it solves #2

[mogul]

Great, thank you!