docs(observability): update operational-alerts.md — add netclaw config Telemetry & Alerting callout (post-netclaw-dev/netclaw#1368)

[Aaronontheweb]

Context

Update src/content/docs/observability/operational-alerts.md after netclaw-dev/netclaw#1368 ships.

Current

Only documents JSON editing of the Notifications.Webhooks array. The netclaw config multi-webhook editor is undocumented.

Should become

Add a callout (tip/note admonition) at the top of the webhook configuration section:

Easiest way: run netclaw config → Telemetry & Alerting to add, remove, or test notification webhooks via the interactive multi-webhook list editor. No JSON editing required.

Keep existing JSON documentation below the callout — it remains valid for advanced/scripted use. The callout surfaces the GUI path first.

Optionally insert config-telemetry.png from sub-issue #13 to illustrate.

Screenshots or tapes needed

config-telemetry from sub-issue #13 (optional). Screenshot insertion gated on stable release.

Acceptance criteria

• Callout added pointing to netclaw config → Telemetry & Alerting for webhook management
• Multi-webhook list editor mentioned (add / remove / test)
• Existing JSON documentation retained

Dependencies

• Can start now — no binary required
• Sub-issue docs(cli): new page cli/config.md — netclaw config dashboard reference (post-netclaw-dev/netclaw#1368) #59 (cli/config.md) for cross-link
• Sub-issue Update exposure/pairing docs and homepage hero copy #13 for optional config-telemetry screenshot

Part of #55