Complete documentation refactoring with 57 service docs

- Refactored README.md, getting-started.md, quick-reference.md
- Enhanced setup-homelab.sh with 9-step automated process
- Created services-overview.md with all stacks
- Added comprehensive documentation for 57 services in docs/service-docs/
- All services include: overview, configuration, resources, educational content
- Coverage: Core, Infrastructure, Dashboards, Media, Media-Extended, Home Assistant, Productivity, Utilities, Monitoring, Development stacks
- Educational focus with links to tutorials, videos, and guides

docs/service-docs/node-exporter.md

@@ -0,0 +1,138 @@
+# Node Exporter - System Metrics
+
+## Table of Contents
+- [Overview](#overview)
+- [What is Node Exporter?](#what-is-node-exporter)
+- [Why Use Node Exporter?](#why-use-node-exporter)
+- [Configuration in AI-Homelab](#configuration-in-ai-homelab)
+- [Official Resources](#official-resources)
+- [Docker Configuration](#docker-configuration)
+
+## Overview
+
+**Category:** Metrics Exporter  
+**Docker Image:** [prom/node-exporter](https://hub.docker.com/r/prom/node-exporter)  
+**Default Stack:** `monitoring.yml`  
+**Purpose:** Export host system metrics  
+**Ports:** 9100
+
+## What is Node Exporter?
+
+Node Exporter is a Prometheus exporter for hardware and OS metrics. It exposes CPU, memory, disk, network, and dozens of other system metrics in Prometheus format. Essential for monitoring your server health.
+
+### Key Features
+- **Hardware Metrics:** CPU, memory, disk, network
+- **OS Metrics:** Load, uptime, processes
+- **Filesystem:** Disk usage, I/O
+- **Network:** Traffic, errors, connections
+- **Temperature:** CPU/disk temps (if available)
+- **Lightweight:** Minimal overhead
+- **Standard:** Official Prometheus exporter
+
+## Why Use Node Exporter?
+
+1. **Essential:** Core system monitoring
+2. **Comprehensive:** 100+ metrics
+3. **Standard:** Official Prometheus exporter
+4. **Lightweight:** Low resource usage
+5. **Reliable:** Battle-tested
+6. **Grafana Dashboards:** Many pre-made
+
+## Configuration in AI-Homelab
+
+```
+Node Exporter runs on host network mode to access system metrics.
+```
+
+## Official Resources
+
+- **GitHub:** https://github.com/prometheus/node_exporter
+- **Metrics:** https://github.com/prometheus/node_exporter#enabled-by-default
+
+## Docker Configuration
+
+```yaml
+node-exporter:
+  image: prom/node-exporter:latest
+  container_name: node-exporter
+  restart: unless-stopped
+  network_mode: host
+  pid: host
+  command:
+    - '--path.procfs=/host/proc'
+    - '--path.sysfs=/host/sys'
+    - '--path.rootfs=/host'
+    - '--collector.filesystem.mount-points-exclude=^/(sys|proc|dev|host|etc)($$|/)'
+  volumes:
+    - /proc:/host/proc:ro
+    - /sys:/host/sys:ro
+    - /:/host:ro,rslave
+```
+
+**Note:** Uses `network_mode: host` to access system metrics directly.
+
+## Metrics Available
+
+### CPU
+- `node_cpu_seconds_total` - CPU time per mode
+- `node_load1` - Load average (1 minute)
+- `node_load5` - Load average (5 minutes)
+- `node_load15` - Load average (15 minutes)
+
+### Memory
+- `node_memory_MemTotal_bytes` - Total memory
+- `node_memory_MemFree_bytes` - Free memory
+- `node_memory_MemAvailable_bytes` - Available memory
+- `node_memory_Buffers_bytes` - Buffer cache
+- `node_memory_Cached_bytes` - Page cache
+
+### Disk
+- `node_filesystem_size_bytes` - Filesystem size
+- `node_filesystem_free_bytes` - Free space
+- `node_filesystem_avail_bytes` - Available space
+- `node_disk_read_bytes_total` - Bytes read
+- `node_disk_written_bytes_total` - Bytes written
+
+### Network
+- `node_network_receive_bytes_total` - Bytes received
+- `node_network_transmit_bytes_total` - Bytes transmitted
+- `node_network_receive_errors_total` - Receive errors
+- `node_network_transmit_errors_total` - Transmit errors
+
+## Summary
+
+Node Exporter provides system metrics offering:
+- CPU usage and load
+- Memory usage
+- Disk space and I/O
+- Network traffic
+- System uptime
+- 100+ other metrics
+- Prometheus format
+- Free and open-source
+
+**Perfect for:**
+- System health monitoring
+- Resource usage tracking
+- Capacity planning
+- Performance analysis
+- Server dashboards
+
+**Key Points:**
+- Official Prometheus exporter
+- Runs on port 9100
+- Host network mode
+- Exports 100+ metrics
+- Grafana dashboard 1860
+- Very lightweight
+- Essential for monitoring
+
+**Remember:**
+- Add to Prometheus scrape config
+- Import Grafana dashboard 1860
+- Monitor disk space
+- Watch CPU and memory
+- Network metrics valuable
+- Low overhead
+
+Node Exporter monitors your server health!