"Installing Helm" tells users to add the now deprecated stable repo

[Poldovico]

At this time, https://helm.sh/docs/intro/install/#from-the-binary-releases tells a new user they should add the stable repo after installing Helm.

This is confusing as the page makes no reference to what the stable repo is, and the link just sends them to the quickstart page, which makes no reference to the stable repo at all and seems to just use bitnami as an example.

A google rabbit hole later, I think the stable repo was an old repo officially maintained by Helm and now there is no such thing and I should use the artifact hub instead?

This should probably be updated, especially when it's quite likely someone viewing the intallation page will have no historical context on this whatsoever. Maybe even add historical context so users can figure out what to make of any references to "the stable repo" they might find in the wild?

[TerryHowe]

Maybe it would be more clear if it said [add the stable chart repository](https://helm.sh/docs/intro/quickstart/#initialize-a-helm-chart-repository) I think that is the intention

[TerryHowe]

Should be closed by #1652

I pasted the wrong url in the PR.