Prometheus-kube-stack Add documentation to Readme for third-party applications in a different namespace

[cccsss01]

Is your feature request related to a problem ?

I'm finding it difficult configuring scrapeMonitors to scrape third-part applications in a different namespace. Hoping we can add some documentation to address this. Most specifically interested in serviceMonitorNamespaceSelector and not serviceMonitorSelectorNilUsesHelmValues: false
with mTLS would be huge!

Describe the solution you'd like.

I would be greatly appreciative of adding this documentation to the readme for prometheus-kube-stack

Describe alternatives you've considered.

Trying to tie in prometheus-operator prometheus and kube-stack prometheus all in one

Additional context.

No response

[cccsss01]

I'll submit a PR

[antinova]

@cccsss01 any update?