Add .github/agents documentation and tour steps across all tracks

[Copilot]

Addresses missing documentation for .github/agents/ feature. Users need to understand repository-level AI assistants and nested folder context enrichment.

Changes

Documentation files

• dotNet/src/Agents.md
• Typescript/Agents.md
• cpp/src/Agents.md

Each covers:

• GitHub Copilot Agents overview
• Link to agents.md for discovering available AI assistants
• Nested folder structure examples for context enrichment
• Differentiation between chat modes (user-level) vs agents (repo-level)

Tour steps

Added educational steps positioned after custom chat mode sections:

• .NET: Step 37/40
• TypeScript: Step 20/23
• C++: Step 26/28

Example nested structure explained:

.github/agents/
├── tour-agent.md              # General purpose
├── backend/
│   └── api-reviewer.md        # Backend-specific with deeper context
└── frontend/
    └── ui-helper.md           # Frontend-specific with deeper context

Tour steps emphasize:

• Multiple AI assistants available out-of-the-box via agents.md
• Nested folders provide richer context for specialized work
• Version-controlled team collaboration vs personal chat modes

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Missing feature: Agents.md</issue_title>
<issue_description>1. Create an Agents.md step within the repo.
2. Create an a step explaining about.github/Agents.md. Make sure to direct the attention to the site agents.md and instruct users to see how many AI Assistants it supports off the bat. Make sure to include it can be nested in multiple folders to further enrich context upon deep dives. </issue_description>

Comments on the Issue (you are @copilot in this section)

Note

Custom agent used: Bob-the-builder
Specific code-tour building agent

• Fixes Missing feature: Agents.md #29

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