[doc] barebone version

Hi, just FYI I've setup a workflow that uses plain `helm` without GitHub Pages: https://github.com/ironpeakservices/iron-chart-go/blob/master/.github/workflows/release.yml

Might be interesting for others.
You install via
```shell
# first add our helm repository
# provide a GitHub token if it's private
% helm repo add ironchartgo https://${GITHUB_TOKEN}@raw.githubusercontent.com/ironpeakservices/iron-chart-go/helmrepo/
"ironchartgo" has been added to your repositories

# now let's install our Chart from our repository
% helm install mychart ironchartgo/iron-chart-go
```