Promote troubleshooting to a standalone docs page

[vortacity]

Problem

The only troubleshooting content is a 6-row table at the end of docs/demo-tenant-setup.md. Someone whose monitor shows nothing, or whose deploy 403s, won't find it — it's buried in a demo-setup guide they may never open.

Proposal

Create docs/troubleshooting.md organized by symptom rather than by component, e.g.:

• "monitor shows nothing after demo-access" (UAL latency: 60–90 min typical, up to 12h for a new subscription)
• "auth succeeds but deploy returns 403" (admin consent, permission grants)
• "first poll returns no content" (subscription just started)

Move/expand the existing table, include the expected-latency decision table, link it from the README Documentation list and from the demo guide.

[laishettikarthik-tech]

Hi @vortacity, I'd like to work on this. I'll create docs/troubleshooting.md by extracting and expanding the existing table from demo-tenant-setup.md, organized by symptom, and link it from both the README and the demo guide. Let me know if you have any preferences on structure before I start.