Documentation: additional explainer for the pod-selector

[mrsimonemms]

Proposed change

Improves the documentation for the gethomepage.dev/pod-selector annotation on the automatic service discovery page. There's at least two discussions about this resulting in NOT FOUND on the service health icon, so this explains why that's happening and how to fix it.

Discussions:

• [BUG] Kubernetes service status check fails when ingress name differs from service name #3781
• Why is my Grafana service showing as "not found"? #4297

Closes # (issue)

Type of change

• New service widget
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Documentation only
• Other (please explain)

Checklist:

• If applicable, I have added corresponding documentation changes.
• If applicable, I have reviewed the feature and / or service widget guidelines.
• I have checked that all code style checks pass using pre-commit hooks and linting checks.
• If applicable, I have tested my code for new features & regressions on both mobile & desktop devices, using the latest version of major browsers.

[mrsimonemms]

Thanks @shamoon, hopefully this is closer to what you'd like to see.

[shamoon]

That's great thanks!