📖 docs: add AGENT_USAGE_GUIDE.md and update README with agent launch commands

- Created comprehensive agent usage guide in documentation/
- Added quick launch commands to README
- Provides clear guidance on when to use each agent
- Includes workflow examples and best practices
- Links to full documentation for details

This makes it easier for new users to:
- Launch the correct agent for their task
- Follow established workflows
- Understand agent capabilities
- Find troubleshooting help

Refs: #documentation, #onboarding, #usability

README.md

@@ -321,6 +321,31 @@ The Gitea client skill enables AI agents to:
 
 **Documentation:** See [.vibe/skills/gitea-client/README.md](.vibe/skills/gitea-client/README.md) for complete setup and usage guide.
 
+## 🤖 AI Agent Usage
+
+### Quick Launch Commands
+
+**Programmer Agent** (for code implementation, testing, CI/CD):
+```bash
+vibe start --agent dancelessonscoachprogrammer
+```
+
+**Product Owner Agent** (for requirements, interviews, documentation):
+```bash
+vibe start --agent dancelessonscoach-product-owner
+```
+
+### Full Documentation
+
+For complete agent usage guide including:
+- Agent selection guidance
+- Common workflow examples
+- Configuration reference
+- Best practices
+- Troubleshooting tips
+
+See: [AGENT_USAGE_GUIDE.md](documentation/AGENT_USAGE_GUIDE.md)
+
 ## License
 
 MIT