Docs: Add example notification automations using the binary sensor alerts

[GreenNovaEmma]

Problem

The sensor package includes four ready-to-use binary sensors for triggering alerts, but there are no example automations showing users how to wire these up to notifications. Users have to figure out the automation YAML themselves.

Binary sensors available

• binary_sensor.migraine_risk_warning — True when risk score ≥ 8 (High/Very High)
• binary_sensor.pressure_drop_alert_4hpa — True when 6h or 24h pressure drop ≥ 4hPa
• binary_sensor.poor_air_today — True when AQI > 100 or PM2.5 ≥ 25 µg/m³
• binary_sensor.migraine_lightning_alert — True when active thunderstorm warning

Proposed additions

Add an examples/ folder (or section in README) with copy-paste automation YAML for common use cases:

1. Morning daily briefing — notify at 7am if today's risk is Moderate or higher
2. Immediate pressure alert — notify when a significant pressure drop is detected
3. Compound trigger — notify when 2+ factors are elevated simultaneously
4. Pre-emptive medication reminder — notify when risk rises to High, with a 4-hour snooze

Each example should show:

• Mobile app notification (notify.mobile_app_*)
• The binary sensor or template trigger
• Optional conditions (e.g., time of day, not already notified today)

Format

YAML files in examples/automations/ so users can import directly via the HA UI.