Set up agent instructions

[Copilot]

Adds agent instructions file and corrects outdated documentation metadata about the build process.

Changes

• AGENTS.md: Agent instructions following repository convention

  • Scope/constraints: documentation-focused, minimal edits, v4 preferred over legacy v2/v3
  • Do/Don't table for common patterns (.md links not .html, run docfx builds, update toc.yml)
  • Delegates to READMEs as source of truth for build/content workflows

• build/README.md: Fixed "What does the script do?" section

  • Was: "Install docfx via dotnet tool restore from .config/dotnet-tools.json"
  • Now: "Download docfx binaries (temporary .NET 10 workaround)"
  • Reflects actual build-metadata.ps1 implementation

• docs/README.md: Fixed "Installing docfx" section

  • Removed non-existent .config/dotnet-tools.json reference
  • Clarified docfx auto-downloads via build-metadata.ps1

Original prompt

---

This section details on the original issue you should resolve

<issue_title>✨ Set up Copilot instructions</issue_title>
<issue_description>Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

</issue_description>

<agent_instructions>This repo is heavily dependent on docfx</agent_instructions>

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

• Fixes ✨ Set up Copilot instructions #425

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[TimHess]

@copilot update metadata based on latest changes

[Copilot]

@copilot update metadata based on latest changes

Updated in f94b2db. Corrected outdated references to .config/dotnet-tools.json in both build/README.md and docs/README.md to reflect the actual implementation where docfx binaries are downloaded directly by build-metadata.ps1 as a temporary workaround for .NET 10 support.

[github-actions]

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