Add or enhance example usage guide for agent instruction templates

[dieterbaier]

Goal

Improve the discoverability and usability of the new agent instruction templates (templates/agents/) by ensuring there is clear, accessible example documentation or onboarding guide that shows new projects how to bootstrap with these templates.

Rationale

PR #29 introduces three new agent instruction templates:

• templates/agents/global-agent-instructions.md
• templates/agents/project-agents.md
• templates/agents/github-copilot-instructions.md

However, it may not be immediately clear to new users or projects:

1. Where these templates are located
2. How to use them in a new project setup
3. What the relationship and priority order is between the three templates
4. Where to copy them and what to customize

First Step: Audit Existing Documentation

Before implementing this improvement, audit the existing documentation to check whether:

• An onboarding guide or README in templates/agents/ already exists that explains template usage
• The main repository README.md already contains links to or references these templates
• The skills/bootstrap-project/SKILL.md already provides sufficiently clear copy-paste examples (including which template goes where and what to customize)
• Any other high-level documentation already guides new projects to these templates

If any of these exist but feel unclear, document which ones need improvement.

Implementation

If gaps are found, create or enhance documentation to include:

1. A top-level guide (e.g., templates/agents/README.md or a section in the main README) that explains:

   • What the three templates are for
   • The execution order (global → project → skill)
   • When to use each template
   • Link to skills/bootstrap-project/SKILL.md for detailed setup instructions

2. Concrete examples showing:

   • Where to place each template in a sample project
   • What variables to replace (e.g., <project>, <toolkit-url>)
   • How each template references the others

3. Quick-start checklist for new projects adopting the toolkit

Definition of Done

• Audit complete; existing coverage documented in issue comments
• If gaps exist: new or enhanced guide is in place and easy to find from main README
• Examples or copy-paste instructions are concrete (not abstract)
• Relationship between the three templates is crystal clear to a first-time reader