[Docs]: GitHub Copilot lacks a dedicated documentation page

[flanny7]

Hello, I always appreciate rulesync.

Problem

Rulesync has a dedicated documentation page for Takt (docs/tools/takt.md), but there is no equivalent page for GitHub Copilot despite it being one of the most widely used tools in the supported set.

Missing Content

A dedicated /docs/tools/copilot.md page should cover at minimum:

1. Output file locations

   • Project mode root: .github/copilot-instructions.md
   • Project mode non-root: .github/instructions/*.instructions.md
   • Global mode root: ~/.copilot/copilot-instructions.md

2. Frontmatter fields specific to Copilot rules

   • applyTo — comma-separated glob patterns that control which files the rule applies to
   • description — human-readable description of the rule
   • excludeAgent — "code-review" or "coding-agent" to exclude specific Copilot agents

3. Root vs. non-root rules

   • Root copilot-instructions.md has no frontmatter
   • Non-root *.instructions.md files support the frontmatter fields above

4. Known limitations

   • CopilotSkill does not support global mode (throws an error)
   • Ignore and Permissions features are not yet supported

5. Copilot vs. Copilot CLI — brief comparison of copilot and copilotcli targets

Reference

docs/reference/file-formats.md and docs/guide/global-mode.md contain scattered Copilot-related content that could be consolidated into this new page.

Your consideration would be appreciated.