docs: add plugin-dev-guide to Available Commands table (#200)

## Summary

Adds the `/plugin-dev:plugin-dev-guide` command to its own "Available
Commands" table for consistency.

## Changes

- Added missing command entry to the table in
`plugins/plugin-dev/skills/plugin-dev-guide/SKILL.md`

## Test plan

- [x] Verify table now lists all 4 commands

Fixes #199

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: sjnims

plugins/plugin-dev/skills/plugin-dev-guide/SKILL.md

@@ -14,7 +14,7 @@ The plugin-dev toolkit provides 9 specialized skills for building Claude Code pl
 ### Skill Quick Reference
 
 | Skill                     | Purpose                                            |
-| -------                   | ---------                                          |
+| ------------------------- | -------------------------------------------------- |
 | **plugin-structure**      | Directory layout, manifest, component organization |
 | **command-development**   | Slash commands with frontmatter                    |
 | **agent-development**     | Autonomous subagents                               |
@@ -183,21 +183,22 @@ User wants to...
 
 The plugin-dev plugin also provides 3 agents:
 
-| Agent | Purpose |
-|-------|---------|
+| Agent                | Purpose                                  |
+| -------------------- | ---------------------------------------- |
 | **plugin-validator** | Validates plugin structure and manifests |
-| **skill-reviewer** | Reviews skill quality and triggering |
-| **agent-creator** | Generates new agents from descriptions |
+| **skill-reviewer**   | Reviews skill quality and triggering     |
+| **agent-creator**    | Generates new agents from descriptions   |
 
 Use agents proactively after creating components to ensure quality.
 
 ## Available Commands
 
-| Command | Purpose |
-|---------|---------|
-| `/plugin-dev:start` | Entry point - choose plugin or marketplace creation |
-| `/plugin-dev:create-plugin` | 8-phase guided plugin creation workflow |
-| `/plugin-dev:create-marketplace` | 8-phase guided marketplace creation workflow |
+| Command                          | Purpose                                             |
+| -------------------------------- | --------------------------------------------------- |
+| `/plugin-dev:plugin-dev-guide`   | Overview and skill routing                          |
+| `/plugin-dev:start`              | Entry point - choose plugin or marketplace creation |
+| `/plugin-dev:create-plugin`      | 8-phase guided plugin creation workflow             |
+| `/plugin-dev:create-marketplace` | 8-phase guided marketplace creation workflow        |
 
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