Add comprehensive Uptime Kuma management documentation

Complete documentation for monitor and tag management workflows:

New documentation:
- README.md: Quick reference and complete workflow guide
- TAG_MANAGEMENT.md: Comprehensive tag management strategies
- tag_monitor.sh: Quick CLI script to tag monitors

Updated documentation:
- API.md: Added tag management section with quick reference

Coverage:
- Adding monitors with tags (complete workflow)
- Updating and deleting monitors
- Tag management strategies and patterns
- Common tagging patterns by service type
- Troubleshooting guide
- Best practices and maintenance tasks

All common operations are now documented with examples.

uptime-kuma/API.md

@@ -203,6 +203,45 @@ api.delete_monitor(1)
 api.disconnect()
 ```
 
+## Tag Management
+
+Tags help organize monitors by category. See [TAG_MANAGEMENT.md](TAG_MANAGEMENT.md) for comprehensive tag documentation.
+
+### Quick Tag Commands
+
+**Tag a new monitor:**
+```bash
+# After creating a monitor, tag it quickly
+./tag_monitor.sh MONITOR_ID TAG_ID [TAG_ID...]
+
+# Example: Tag monitor 15 as application + web
+./tag_monitor.sh 15 3 4
+```
+
+**View all tags:**
+```bash
+./check_tags.py
+```
+
+**Common Tag IDs:**
+- 1=hardware, 2=monitoring, 3=application, 4=web, 5=database
+- 6=media, 7=infrastructure, 8=storage, 9=virtualization, 10=vm
+
+**Full workflow for adding a tagged monitor:**
+```bash
+# 1. Add monitor and note the ID
+./manage_monitors.py add --name "New Service" --url "https://example.com"
+./manage_monitors.py list | grep "New Service"
+
+# 2. Tag it
+./tag_monitor.sh 16 3 4  # application + web
+
+# 3. Verify
+./check_tags.py | grep "New Service"
+```
+
+For detailed tagging strategies and workflows, see **[TAG_MANAGEMENT.md](TAG_MANAGEMENT.md)**.
+
 ## References
 
 - [Uptime Kuma API Keys Documentation](https://github.com/louislam/uptime-kuma/wiki/API-Keys)