docs: admin guide (install, voip.ms, network, E911, troubleshooting, updating)

docs/admin-guide/: install and the setup wizard, voip.ms with screenshots, NAT and SIP
ALG, firewall (ufw, nftables limited to the voip.ms POP), fail2ban and CrowdSec, E911
duties, recording consent, troubleshooting (08 §3.3), updating, backup and restore,
monitoring and log rotation. scripts/update.sh as 08 §3.1 describes. The e2e checks
fail2ban's and CrowdSec's stock Asterisk rules against a real failed sign-in, takes the
screenshots and checks every link and anchor.

Task: M11-T7

README.md

@@ -5,8 +5,9 @@ browser softphone, voicemail to email, IVRs, ring groups, queues, office hours,
 recording, live dashboard, SMS and phone provisioning. Bring your own SIP trunk and
 numbers (reference provider: voip.ms). Built on Asterisk 24 LTS + TypeScript + PostgreSQL 18.
 
-**Status:** specification stage. Nothing is built yet.
+**Status:** pre-1.0, not yet tested by an outside installer.
 
+- Installing and running it: the [admin guide](docs/admin-guide/README.md)
 - Start here if you are writing code (human or AI): [`AGENTS.md`](AGENTS.md)
 - The full spec: [`docs/spec/`](docs/spec/00-overview.md)
 - Build order: [`docs/spec/09-roadmap.md`](docs/spec/09-roadmap.md)