docs: add ${CLAUDE_PLUGIN_ROOT} explanation to marketplace-structure skill

[sjnims]

Summary

Add explanatory note for the ${CLAUDE_PLUGIN_ROOT} environment variable in the marketplace-structure skill's schema reference documentation.

Problem

Fixes #95

The ${CLAUDE_PLUGIN_ROOT} environment variable is used in the hooks and mcpServers examples within the Complete Plugin Entry Example, but wasn't explicitly explained. Users unfamiliar with plugin development may not understand what this variable represents.

Solution

Added a brief note directly before the Complete Plugin Entry Example that explains:

• What ${CLAUDE_PLUGIN_ROOT} resolves to (plugin's absolute installation path)
• When to use it (hooks and MCP server configurations)
• Why it matters (portable paths regardless of installation location)

This approach was chosen over adding a new subsection because:

1. It's contextual - explains the variable right where it's used
2. Simpler and less intrusive to the document structure
3. Provides just-in-time information for users reading the example

Alternatives Considered

• New "### Environment Variables" subsection after Component Configuration Fields - More prominent but disrupts document flow and may be overkill for a single variable note
• Inline code comment in the JSON example - Would require multiple comments and break JSON syntax highlighting

Changes

• plugins/plugin-dev/skills/marketplace-structure/references/schema-reference.md: Added note before Complete Plugin Entry Example explaining ${CLAUDE_PLUGIN_ROOT}

Testing

• markdownlint passes
• No other files affected

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PR Review Complete ✅

Reviewing PR #97: docs: add ${CLAUDE_PLUGIN_ROOT} explanation to marketplace-structure skill

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Summary

Looks good! This is a valuable documentation improvement that addresses a real gap in the marketplace-structure skill.

What's Good

1. Contextual Placement: The note is placed immediately before the Complete Plugin Entry Example, exactly where users encounter ${CLAUDE_PLUGIN_ROOT} in the code. This is "just-in-time" documentation at its best.

2. Clear and Concise: The explanation covers all three essential points:

   • What it is: "plugin's absolute installation path"
   • When to use it: "hooks and MCP server configurations"
   • Why it matters: "portable paths regardless of where the plugin is installed"

3. Writing Quality: The note uses clear, technical language appropriate for the plugin-dev audience.

4. Markdown Linting: ✅ All markdown style rules pass (markdownlint reports no issues).

5. Scope Discipline: The PR correctly resists over-engineering. Adding a dedicated subsection would be overkill for a single environment variable that's only used in specific contexts.

6. Alignment with CLAUDE.md: This change aligns perfectly with the repository's convention stated in CLAUDE.md line 70: "Always use ${CLAUDE_PLUGIN_ROOT} for portable paths in hooks, MCP configs, and scripts."

Suggestions

None - this PR is ready to merge as-is.

Checklist Verification

• ✅ Fixes stated issue ([Docs]: Add explanation for ${CLAUDE_PLUGIN_ROOT} in marketplace-structure skill #95)
• ✅ Markdown linting passes
• ✅ No unnecessary structural changes
• ✅ Documentation is clear and helpful
• ✅ Placement is contextually appropriate
• ✅ Follows repository conventions

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Recommendation: Approve and merge. This is a focused, helpful documentation improvement that addresses user confusion without introducing unnecessary complexity.

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